{"id":4637,"date":"2020-09-27T15:37:06","date_gmt":"2020-09-27T07:37:06","guid":{"rendered":"https:\/\/damogame.cn\/wordpress\/?p=4637"},"modified":"2020-09-27T15:37:06","modified_gmt":"2020-09-27T07:37:06","slug":"%e5%89%96%e6%9e%90stdfunction%e6%8e%a5%e5%8f%a3%e4%b8%8e%e5%ae%9e%e7%8e%b0","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/4637","title":{"rendered":"\u5256\u6790std::function\u63a5\u53e3\u4e0e\u5b9e\u73b0"},"content":{"rendered":"<p><a href=\"https:\/\/www.cnblogs.com\/jerry-fuyi\/p\/std_function_interface_implementation.html\">\u539f\u6587\u5730\u5740<\/a><\/p>\n<h3><\/h3>\n<h3>\u524d\u8a00<\/h3>\n<p>\u4e3a\u4ec0\u4e48\u8981\u5256\u6790\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5462\uff1f\u56e0\u4e3a\u7b14\u8005\u6700\u8fd1\u5728\u505a\u4e00\u4e2a\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5411\u5355\u7247\u673a\u7cfb\u7edf\u7684\u79fb\u690d\u4e0e\u6269\u5c55\u3002<\/p>\n<p>\u540e\u7eed\u8fd8\u4f1a\u6709\u00a0<span class=\"cnblogs_code\">std::bind<\/span>\u00a0\u7b49\u6807\u51c6\u5e93\u5176\u4ed6\u90e8\u5206\u7684\u79fb\u690d\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_1\"><\/a>\u4e00\u3001std::function\u7684\u539f\u7406\u4e0e\u63a5\u53e3<\/h3>\n<h3><a name=\"mark_1_1\"><\/a>1.1\u00a0std::function\u662f\u51fd\u6570\u5305\u88c5\u5668<\/h3>\n<p><span class=\"cnblogs_code\">std::function<\/span>\u00a0\uff0c\u80fd\u5b58\u50a8\u4efb\u4f55\u7b26\u5408\u6a21\u677f\u53c2\u6570\u7684\u51fd\u6570\u5bf9\u8c61\u3002\u6362\u53e5\u8bdd\u8bf4\uff0c\u8fd9\u4e9b\u62e5\u6709\u4e00\u81f4\u53c2\u6570\u7c7b\u578b\u3001\u76f8\u540c\u8fd4\u56de\u503c\u7c7b\u578b\uff08\u5176\u5b9e\u4e0d\u5fc5\u5b8c\u5168\u76f8\u540c\uff09\u7684\u51fd\u6570\u5bf9\u8c61\uff0c\u53ef\u4ee5\u7531\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7edf\u4e00\u5305\u88c5\u8d77\u6765\u3002\u51fd\u6570\u5bf9\u8c61\u7684\u5927\u5c0f\u662f\u4efb\u610f\u7684\u3001\u4e0d\u80fd\u786e\u5b9a\u7684\uff0c\u800cC++\u4e2d\u7684\u7c7b\u578b\u90fd\u662f\u56fa\u5b9a\u5927\u5c0f\u7684\uff0c\u90a3\u4e48\uff0c\u5982\u4f55\u5728\u4e00\u4e2a\u56fa\u5b9a\u5927\u5c0f\u7684\u7c7b\u578b\u4e2d\u5b58\u50a8\u4efb\u610f\u5927\u5c0f\u7684\u5bf9\u8c61\u5462\uff1f<\/p>\n<p>\u5b9e\u9645\u4e0a\u95ee\u9898\u8fd8\u4e0d\u6b62\u5b58\u50a8\u90a3\u4e48\u7b80\u5355\u3002\u5b58\u50a8\u4e86\u51fd\u6570\u5bf9\u8c61\uff0c\u5fc5\u5b9a\u662f\u8981\u5728\u67d0\u4e00\u65f6\u523b\u8c03\u7528\uff1b\u51fd\u6570\u5bf9\u8c61\u4e0d\u662f\u5728\u521b\u5efa\u7684\u65f6\u5019\u8c03\u7528\uff0c\u8fd9\u4e2a\u7279\u6027\u6210\u4e3a\u5ef6\u8fdf\u8c03\u7528\uff1b\u51fd\u6570\u5bf9\u8c61\u4e5f\u662f\u5bf9\u8c61\uff0c\u9700\u8981\u5904\u7406\u597d\u6784\u9020\u3001\u62f7\u8d1d\u3001\u79fb\u52a8\u3001\u6790\u6784\u7b49\u95ee\u9898\u2014\u2014\u8fd9\u4e9b\u4e5f\u9700\u8981\u5ef6\u8fdf\u8c03\u7528\uff0c\u4f46\u603b\u4e0d\u80fd\u518d\u7528\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u6765\u89e3\u51b3\u5427\uff1f<\/p>\n<p>\u65e2\u7136\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u80fd\u5b58\u50a8\u4e0d\u540c\u7c7b\u578b\u7684\u51fd\u6570\u5bf9\u8c61\uff0c\u53ef\u4ee5\u8bf4\u5b83\u5177\u6709\u591a\u6001\u6027\u3002C++\u4e2d\u4f53\u73b0\u591a\u6001\u6027\u7684\u4e3b\u8981\u662f\u865a\u51fd\u6570\uff0c\u7ee7\u627f\u4e0e\u591a\u6001\u8fd9\u4e00\u5957\u4f53\u5236\u662f\u53ef\u4ee5\u89e3\u51b3\u8fd9\u4e2a\u95ee\u9898\u7684\u3002<a title=\"Naive std::function implementation\" href=\"https:\/\/shaharmike.com\/cpp\/naive-std-function\/\" target=\"_blank\" rel=\"noopener noreferrer\">\u76f8\u5173\u8d44\u6599[1]<\/a>\u00a0<a title=\"How is std::function implemented?\" href=\"https:\/\/stackoverflow.com\/questions\/18453145\/how-is-stdfunction-implemented\" target=\"_blank\" rel=\"noopener noreferrer\">[2]<\/a>\u4e2d\u7684\u5b9e\u73b0\u5229\u7528\u4e86\u7ee7\u627f\u4e0e\u591a\u6001\uff0c\u76f8\u5f53\u7b80\u6d01\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_1_2\"><\/a>1.2 C++\u6ce8\u91cd\u8fd0\u884c\u65f6\u6548\u7387<\/h3>\n<p>\u5229\u7528\u7ee7\u627f\u4e0e\u591a\u6001\uff0c\u6211\u4eec\u53ef\u4ee5\u8ba9\u7f16\u8bd1\u5668\u5e2e\u6211\u4eec\u641e\u5b9a\u51fd\u6570\u5bf9\u8c61\u7684\u6790\u6784\u3002\u5c31\u8fd9\u79cd\u5b9e\u73b0\u800c\u8a00\uff0c\u8fd9\u662f\u7b80\u6d01\u800c\u6709\u6548\u7684\u65b9\u6cd5\u3002\u7136\u800c\u8fd9\u79cd\u5b9e\u73b0\u9700\u8981\u52a8\u6001\u5185\u5b58\uff0c\u5728\u4e00\u4e9b\u60c5\u51b5\u4e0b\u4e0d\u5212\u7b97\uff0c\u751a\u81f3\u5b8c\u5168\u6ca1\u6709\u5fc5\u8981\u3002C++11\u5f15\u5165\u4e86lambda\u8868\u8fbe\u5f0f\uff0c\u5176\u672c\u8d28\u4e5f\u662f\u51fd\u6570\u5bf9\u8c61\u3002\u8fd9\u4e2a\u5bf9\u8c61\u6709\u591a\u5927\u5462\uff1f\u53d6\u51b3\u4e8e\u6355\u83b7\u5217\u8868\u3002\u4f60\u5199lambda\u4f1a\u6355\u83b7\u591a\u5c11\u4e1c\u897f\uff1f\u5f88\u591a\u60c5\u51b5\u4e0b\u5c31\u53ea\u662f\u4e00\u5bf9\u65b9\u62ec\u53f7\u800c\u5df2\u5427\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0clambda\u8868\u8fbe\u5f0f\u7684\u5bf9\u8c61\u5927\u5c0f\u53ea\u67091\u5b57\u8282\uff08\u56e0\u4e3a\u4e0d\u80fd\u662f0\u5b57\u8282\uff09\uff0c\u4f60\u5374\u4e3a\u4e86\u8fd9\u6ca1\u6709\u5185\u5bb9\u76841\u5b57\u8282\u8981\u8c03\u7528\u52a8\u6001\u5185\u5b58\u7684\u51fd\u6570\uff1fC++\u6ce8\u91cd\u8fd0\u884c\u65f6\u6548\u7387\uff0c\u8fd9\u79cd\u6d6a\u8d39\u662f\u4e0d\u80fd\u63a5\u53d7\u7684\u3002<\/p>\n<p>\u5982\u4f55\u907f\u514d\u8fd9\u79cd\u6d6a\u8d39\u5462\uff1f\u4f60\u4e5f\u8bb8\u4f1a\u8bf4\u6211\u68c0\u67e5\u4f20\u5165\u7684\u5bf9\u8c61\u662f\u4e0d\u662f1\u5b57\u8282\u7684\u7a7a\u7c7b\u578b\u3002\u4e14\u4e0d\u8bba\u8fd9\u4e2atrait\u600e\u4e48\u5b9e\u73b0\uff0c\u51fd\u6570\u6307\u9488\u3001\u6355\u83b7\u4e00\u4e2aint\u7684lambda\u7b49\u7c7b\u578b\u90fd\u58f0\u79f0\u81ea\u5df1\u662ftrivial\u7684\u5c0f\u5bf9\u8c61\uff0c\u4e5f\u4e0d\u5e94\u8be5\u5206\u914d\u5230heap\u4e2d\u53bb\u3002<\/p>\n<p>\u4e4b\u524d\u8bf4\u8fc7\uff0c<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u5927\u5c0f\u662f\u56fa\u5b9a\u7684\uff0c\u4f46\u662f\u8fd9\u4e2a\u5927\u5c0f\u662f\u53ef\u4ee5\u81ea\u5df1\u5b9a\u7684\u3002\u6211\u4eec\u53ef\u4ee5\u5728\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u7c7b\u5b9a\u4e49\u4e2d\u52a0\u5165\u4e00\u4e2a\u7a7a\u767d\u7684\u3001\u5927\u5c0f\u9002\u4e2d\u7684field\uff0c\u7528\u5728\u5b58\u653e\u8fd9\u4e9b\u5c0f\u5bf9\u8c61\uff0c\u4ece\u800c\u907f\u514d\u8fd9\u4e9b\u60c5\u51b5\u4e0b\u7684\u52a8\u6001\u5185\u5b58\u64cd\u4f5c\u3002\u540c\u65f6\uff0c\u65e2\u7136\u6709\u4e86\u8fd9\u7247\u7a7a\u95f4\uff0c\u4e5f\u5c31\u4e0d\u9700\u8981\u770b\u4f20\u5165\u7684\u5bf9\u8c61\u662f\u4e0d\u662f1\u5b57\u8282\u7684\u7a7a\u7c7b\u578b\u4e86\u3002<\/p>\n<p>\u800c\u5bf9\u4e8e\u66f4\u5927\u7684\u7c7b\u578b\uff0c\u867d\u7136\u8fd9\u4e2afield\u4e0d\u8db3\u4ee5\u5b58\u653e\u51fd\u6570\u5bf9\u8c61\uff0c\u4f46\u8db3\u4ee5\u5b58\u653e\u4e00\u4e2a\u6307\u9488\uff0c\u8fd9\u79cd\u5206\u65f6\u590d\u7528\u7684\u7ed3\u6784\u53ef\u4ee5\u7528union\u6765\u5b9e\u73b0\u3002\u8fd9\u79cd\u5c0f\u5bf9\u8c61\u76f4\u63a5\u5b58\u50a8\u3001\u5927\u5bf9\u8c61\u5728heap\u4e0a\u5f00\u8f9f\u7a7a\u95f4\u5e76\u5b58\u50a8\u6307\u9488\u7684\u65b9\u6cd5\uff0c\u79f0\u4e3asmall object optimization\u3002<\/p>\n<p>\u5728\u5229\u7528\u7ee7\u627f\u7684\u5b9e\u73b0\u4e2d\uff0c\u51fd\u6570\u5bf9\u8c61\u88ab\u5305\u88c5\u5728\u4e00\u4e2a\u5b50\u7c7b\u4e2d\uff0c<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u4e2d\u6301\u6709\u4e00\u4e2a\u5176\u7236\u7c7b\u7684\u6307\u9488\u3002\u7136\u800c\u4e3a\u4e86\u6548\u7387\uff0c\u6211\u4eec\u9700\u8981\u628a\u7a7a\u767dfield\u548c\u8fd9\u4e2a\u6307\u9488union\u8d77\u6765\u3002union\u603b\u7ed9\u4eba\u4e00\u79cd\u5e95\u5c42\u7684\u611f\u89c9\uff0c\u5728\u4e0d\u786e\u5b9a\u8fd9\u4e2aunion\u5230\u5e95\u5b58\u50a8\u7684\u662f\u4ec0\u4e48\u7684\u65f6\u5019\uff0c\u5f53\u7136\u4e0d\u80fd\u901a\u8fc7\u5176\u4e2d\u7684\u6307\u9488\u53bb\u8c03\u7528\u865a\u51fd\u6570\u3002\u5728\u8fd9\u6837\u7684\u8bbe\u8ba1\u4e2d\uff0c\u591a\u6001\u6027\u4e0d\u518d\u80fd\u7528\u7ee7\u627f\u4f53\u7cfb\u5b9e\u73b0\u4e86\uff0c\u6211\u4eec\u9700\u8981\u53e6\u4e00\u79cd\u5b9e\u73b0\u591a\u6001\u7684\u65b9\u6cd5\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_1_3\"><\/a>1.3 \u7528\u51fd\u6570\u6307\u9488\u5b9e\u73b0\u591a\u6001<\/h3>\n<p>\u56de\u60f3\u4e00\u4e0b\u865a\u51fd\u6570\u662f\u5982\u4f55\u5b9e\u73b0\u7684\uff1f\u5e26\u6709virtual function\u7684\u7c7b\u7684\u5bf9\u8c61\u4e2d\u4f1a\u5b89\u63d2vptr\uff0c\u8fd9\u4e2a\u6307\u9488\u6307\u5411\u4e00\u4e2avtable\uff0c\u8fd9\u4e2avtable\u542b\u6709\u591a\u4e2aslot\uff0c\u91cc\u9762\u542b\u6709\u6307\u5411type_info\u5bf9\u8c61\u7684\u6307\u9488\u4e0e\u51fd\u6570\u6307\u9488\u2014\u2014\u5bf9\uff0c\u6211\u4eec\u9700\u8981\u51fd\u6570\u6307\u9488\uff01\u4e0d\u77e5\u4f60\u6709\u6ca1\u6709\u5728C\u4e2d\u5b9e\u73b0\u8fc7\u591a\u6001\uff0c\u5728\u6ca1\u6709\u8bed\u8a00\u7279\u6027\u7684\u5e2e\u52a9\u4e0b\uff0c\u6bd4\u8f83\u65b9\u4fbf\u7684\u65b9\u6cd5\u662f\u5728struct\u4e2d\u76f4\u63a5\u653e\u51fd\u6570\u6307\u9488\u3002\u5982\u679c\u8981\u50cfC++\u90a3\u6837\u7528\u4e0avptr\u548cvtable\uff0c\u4f60\u5f97\u7ba1\u7406\u597d\u6bcf\u4e2a\u7c7b\u53ca\u5176\u5bf9\u5e94vtable\u7684\u5185\u5bb9\u3002\u4f60\u4ee5\u4e3a\u8fd9\u79cd\u60c5\u51b5\u5728C++\u4e2d\u5c31\u6709\u6240\u597d\u8f6c\u5417\uff1f\u53ea\u6709\u4f60\u7528C++\u7684\u7ee7\u627f\u4f53\u7cfb\uff0c\u7f16\u8bd1\u5668\u624d\u4f1a\u5e2e\u4f60\u505a\u8fd9\u4e9b\u4e8b\u3002\u60f3\u8981\u81ea\u5df1\u5efa\u7acb\u4e00\u4e2a\u4ece\u7c7b\u578b\u5230vptr\u7684\u6620\u5c04\uff0c\u6050\u6015\u4f60\u5f97\u6539\u7f16\u8bd1\u5668\u4e86\u3002\uff08\u66f4\u6b63\uff1aC++14\u5f15\u5165\u4e86\u53d8\u91cf\u6a21\u677f\uff0c\u8bf7\u79fb\u6b65<a href=\"https:\/\/www.cnblogs.com\/jerry-fuyi\/p\/12664787.html#sbo\" target=\"_blank\" rel=\"noopener noreferrer\">C++\u503c\u591a\u6001\uff1a\u4f20\u7edf\u591a\u6001\u4e0e\u7c7b\u578b\u64e6\u9664\u4e4b\u95f4<\/a>\u3002\uff09<\/p>\n<p>vptr\u4e0evtable\u7684\u610f\u4e49\u662f\u4ec0\u4e48\uff1f\u5176\u4e00\uff0c\u6bcf\u4e2a\u57fa\u7c7b\u53ea\u5bf9\u5e94\u4e00\u4e2avptr\uff0c\u5927\u5c0f\u56fa\u5b9a\uff0c\u591a\u91cd\u7ee7\u627f\u4e0b\u4fbf\u4e8e\u7ba1\u7406\uff0c\u4f46\u8fd9\u70b9\u4e0e\u8fd9\u7bc7\u6587\u7ae0\u7684\u4e3b\u9898\u6ca1\u6709\u5173\u8054\uff1b\u5176\u4e8c\uff0c\u5f53\u57fa\u7c7b\u6709\u591a\u4e2a\u865a\u51fd\u6570\u7684\u65f6\u5019\uff0c\u4f7f\u7528vptr\u53ef\u4ee5\u8282\u7701\u5b58\u50a8\u5bf9\u8c61\u7684\u7a7a\u95f4\uff0c\u800c\u5982\u679c\u7528\u51fd\u6570\u6307\u9488\u7684\u8bdd\uff0c\u867d\u7136\u5c11\u4e86\u4e00\u6b21\u5bfb\u5740\uff0c\u4f46\u7ee7\u627f\u5e26\u6765\u7684\u7a7a\u95f4overhead\u53d6\u51b3\u4e8e\u865a\u51fd\u6570\u7684\u6570\u91cf\uff0c\u7531\u4e8e\u81f3\u5c11\u4e00\u4e2a\uff0c\u51fd\u6570\u6307\u9488\u7684\u5360\u7528\u7684\u7a7a\u95f4\u4e0d\u4f1a\u5c11\u4e8evptr\uff0c\u5728\u865a\u51fd\u6570\u6570\u91cf\u8f83\u591a\u7684\u60c5\u51b5\u4e0b\uff0c\u51fd\u6570\u6307\u9488\u5c31\u8981\u5360\u7528\u6bd4\u8f83\u5927\u7684\u7a7a\u95f4\u4e86\u3002<\/p>\n<p>\u65e2\u7136\u6211\u4eec\u5df2\u7ecf\u65e0\u6cd5\u5728\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u4e2d\u4f7f\u7528vptr\uff0c\u6211\u4eec\u4e5f\u5e94\u8be5\u5c3d\u53ef\u80fd\u51cf\u5c11\u51fd\u6570\u6307\u9488\u7684\u6570\u91cf\uff0c\u800c\u8fd9\u53c8\u53d6\u51b3\u4e8e\u8fd9\u4e9b\u51fd\u6570\u7684\u529f\u80fd\uff0c\u8fdb\u4e00\u6b65\u53d6\u51b3\u4e8e\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7c7b\u7684\u63a5\u53e3\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_1_4\"><\/a>1.4\u00a0std::function\u7684\u63a5\u53e3<\/h3>\n<p>\u867d\u7136C++\u6807\u51c6\u89c4\u5b9a\u4e86\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u63a5\u53e3\u5c31\u5e94\u8be5\u662f<a title=\"std::function - cppreference.com\" href=\"https:\/\/en.cppreference.com\/w\/cpp\/utility\/functional\/function\" target=\"_blank\" rel=\"noopener noreferrer\">\u8fd9\u6837<\/a>\uff0c\u6211\u8fd8\u662f\u60f3\u8bf4\u8bf4\u5b83\u4e3a\u4ec0\u4e48\u5e94\u8be5\u662f\u8fd9\u6837\u3002\u5173\u4e8e\u5176\u4ed6\u7684\u4e00\u4e9b\u95ee\u9898\uff0c\u6bd4\u5982\u4fdd\u5b58\u503c\u8fd8\u662f\u4fdd\u5b58\u5f15\u7528\u7b49\uff0c\u53ef\u4ee5\u53c2\u8003<a title=\"The space of design choices for std::function\" href=\"https:\/\/quuxplusone.github.io\/blog\/2019\/03\/27\/design-space-for-std-function\/\" target=\"_blank\" rel=\"noopener noreferrer\">\u76f8\u5173\u8d44\u6599[4]<\/a>\u3002<\/p>\n<p>\u6700\u57fa\u672c\u7684\uff0c<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u662f\u4e00\u4e2a\u6a21\u677f\u7c7b\uff0c\u6a21\u677f\u53c2\u6570\u662f\u4e00\u4e2a\u7c7b\u578b\uff08\u6ce8\u610f\u662f\u4e00\u4e2a\u7c7b\u578b\uff0c\u4e0d\u662f\u597d\u51e0\u4e2a\u7c7b\u578b\uff09\u3002\u6211\u4eec\u53ef\u4ee5\u8fd9\u4e48\u5199\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<pre>std::function&lt;int(double)&gt; f;<\/pre>\n<\/div>\n<p><span class=\"cnblogs_code\">f<\/span>\u00a0\u662f\u4e00\u4e2a\u53ef\u8c03\u7528\u5bf9\u8c61\uff0c\u53c2\u6570\u4e3a\u00a0<span class=\"cnblogs_code\">double<\/span>\uff0c\u8fd4\u56de\u503c\u4e3a\u00a0<span class=\"cnblogs_code\">int<\/span>\u00a0\u3002\u4f60\u4e5f\u8bb8\u4f1a\u95ee\uff0c\u8fd9\u91cc\u65e2\u89c4\u5b9a\u4e86\u53c2\u6570\u7c7b\u578b\u53c8\u89c4\u5b9a\u4e86\u8fd4\u56de\u503c\u7c7b\u578b\uff0c\u600e\u4e48\u5c31\u6210\u4e86\u4e00\u4e2a\u7c7b\u578b\u5462\uff1f\u786e\u5b9e\u662f\u4e00\u4e2a\u7c7b\u578b\uff0c<span class=\"cnblogs_code\">int(double)<\/span>\u00a0\u662f\u4e00\u4e2a\u51fd\u6570\u7c7b\u578b\uff08\u6ce8\u610f\u4e0d\u662f\u51fd\u6570\u6307\u9488\uff09\u3002<\/p>\n<p><span class=\"cnblogs_code\">std::function<\/span>\u00a0\u8981\u5305\u88c5\u6240\u6709\u5408\u9002\u7c7b\u578b\u7684\u5bf9\u8c61\uff0c\u5c31\u5fc5\u987b\u6709\u5bf9\u5e94\u7684\u6784\u9020\u51fd\u6570\uff0c\u6240\u4ee5\u8fd9\u662f\u4e2a\u6a21\u677f\u6784\u9020\u51fd\u6570\u3002\u53c2\u6570\u4e0d\u662f\u901a\u7528\u5f15\u7528\u800c\u662f\u76f4\u63a5<a title=\"How true is \u201cWant Speed? Pass by value\u201d\" href=\"https:\/\/stackoverflow.com\/questions\/21605579\/how-true-is-want-speed-pass-by-value\" target=\"_blank\" rel=\"noopener noreferrer\">\u4f20\u503c<\/a>\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<pre>template &lt;typename F&gt;\r\nfunction(F);<\/pre>\n<\/div>\n<p>\u53ef\u80fd\u662f\u4e3a\u4e86\u8ba9\u7f16\u8bd1\u5668\u5bf9\u7a7a\u5bf9\u8c61\u8fdb\u884c\u4f18\u5316\u3002\u540c\u6837\u8fd8\u6709\u4e00\u4e2a\u6a21\u677f\u8d4b\u503c\u51fd\u6570\uff0c\u53c2\u6570\u662f\u901a\u7528\u5f15\u7528\u3002<\/p>\n<p>\u6bcf\u4e2a\u6784\u9020\u51fd\u6570\u90fd\u6709\u4e00\u4e2a\u6dfb\u52a0\u4e86\u00a0<span class=\"cnblogs_code\">std::allocator_arg_t<\/span>\u00a0\u4f5c\u4e3a\u7b2c\u4e00\u4e2a\u53c2\u6570\u3001\u5185\u5b58\u5206\u914d\u5668\u5bf9\u8c61\u4f5c\u4e3a\u7b2c\u4e8c\u4e2a\u53c2\u6570\u7684\u7248\u672c\uff0cC++17\u4e2d\u5df2\u7ecf\u79fb\u9664\uff08GCC\u4ece\u672a\u63d0\u4f9b\uff0c\u53ef\u80fd\u662f\u56e0\u4e3a\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u5185\u5b58\u5206\u914d\u65e0\u6cd5\u81ea\u5b9a\u4e49\uff09\u3002\u540c\u6837\u5220\u9664\u7684\u8fd8\u6709\u00a0<span class=\"cnblogs_code\">assign<\/span>\u00a0\uff0c\u4e5f\u662f\u4e0e\u5185\u5b58\u5206\u914d\u5668\u76f8\u5173\u7684\u3002<\/p>\n<p>\u53e6\u5916\u6709\u4e00\u4e2a\u4ee5\u00a0<span class=\"cnblogs_code\">std::reference_wrapper<\/span>\u00a0\u4f5c\u4e3a\u53c2\u6570\u7684\u8d4b\u503c\u51fd\u6570\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<pre>template &lt;typename F&gt;\r\nfunction&amp; operator=(std::reference_wrapper&lt;F&gt;) noexcept;<\/pre>\n<\/div>\n<p>\u53ef\u4ee5\u7406\u89e3\u4e3a\u6a21\u677f\u8d4b\u503c\u51fd\u6570\u7684\u7279\u5316\u3002\u6ca1\u6709\u76f8\u5e94\u7684\u6784\u9020\u51fd\u6570\u3002<\/p>\n<p>\u9ed8\u8ba4\u6784\u9020\u51fd\u6570\u3001<span class=\"cnblogs_code\">nullptr_t<\/span>\u00a0\u6784\u9020\u51fd\u6570\u3001<span class=\"cnblogs_code\">nullptr_t<\/span>\u00a0\u62f7\u8d1d\u8d4b\u503c\u51fd\u6570\u90fd\u5c06\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5bf9\u8c61\u7f6e\u7a7a\u3002\u5f53\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5bf9\u8c61\u6ca1\u6709\u4fdd\u5b58\u4efb\u4f55\u51fd\u6570\u5bf9\u8c61\u65f6\uff0c\u00a0<span class=\"cnblogs_code\">operator\u00a0bool()<\/span>\u00a0\u8fd4\u56de\u00a0<span class=\"cnblogs_code\">false<\/span>\u00a0\uff0c\u4e0e\u00a0<span class=\"cnblogs_code\">nullptr_t<\/span>\u00a0\u8c03\u7528\u00a0<span class=\"cnblogs_code\">operator==<\/span>\u00a0\u4f1a\u8fd4\u56de\u00a0<span class=\"cnblogs_code\">true<\/span>\u00a0\uff0c\u5982\u679c\u8c03\u7528\u5c06\u629b\u51fa\u00a0<span class=\"cnblogs_code\">std::bad_function_call<\/span>\u00a0\u5f02\u5e38\u3002<\/p>\n<p>\u867d\u7136\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5c06\u51fd\u6570\u5bf9\u8c61\u5305\u88c5\u4e86\u8d77\u6765\uff0c\u4f46\u7528\u6237\u8fd8\u662f\u53ef\u4ee5\u83b7\u5f97\u539f\u59cb\u5bf9\u8c61\u7684\u3002<span class=\"cnblogs_code\">target_type()<\/span>\u00a0\u8fd4\u56de\u51fd\u6570\u5bf9\u8c61\u7684\u00a0<span class=\"cnblogs_code\">typeid<\/span>\u00a0\uff0c<span class=\"cnblogs_code\">target()<\/span>\u00a0\u6a21\u677f\u51fd\u6570\u5f53\u6a21\u677f\u53c2\u6570\u4e0e\u51fd\u6570\u5bf9\u8c61\u7c7b\u578b\u76f8\u540c\u65f6\u8fd4\u56de\u5176\u6307\u9488\uff0c\u5426\u5219\u8fd4\u56de\u7a7a\u6307\u9488\u3002<\/p>\n<p>\u4f5c\u4e3a\u51fd\u6570\u5305\u88c5\u5668\uff0c<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u4e5f\u662f\u51fd\u6570\u5bf9\u8c61\uff0c\u53ef\u4ee5\u901a\u8fc7\u00a0<span class=\"cnblogs_code\">operator()<\/span>\u00a0\u8c03\u7528\uff0c\u53c2\u6570\u6309\u7167\u6a21\u677f\u53c2\u6570\u4e2d\u58f0\u660e\u7684\u7c7b\u578b\u4f20\u9012\u3002<\/p>\n<p>\u8fd8\u6709\u4e00\u4e9b\u63a5\u53e3\u4e0e\u5927\u90e8\u5206STL\u8bbe\u65bd\u76f8\u4f3c\uff0c\u6709Rule of Five\u89c4\u5b9a\u76845\u4e2a\u65b9\u6cd5\u3001\u00a0<span class=\"cnblogs_code\">swap()<\/span>\u00a0\uff0c\u4ee5\u53ca\u00a0<span class=\"cnblogs_code\">std::swap()<\/span>\u00a0\u7684\u7279\u5316\u7b49\u3002\u53ef\u522b\u5c0f\u770b\u8fd9\u4e2a\u00a0<span class=\"cnblogs_code\">swap()<\/span>\u00a0\uff0c\u5b83\u6709\u5927\u7528\u5904\u3002<\/p>\n<p>\u603b\u4e4b\uff0c\u51fd\u6570\u5bf9\u8c61\u7684\u590d\u5236\u3001\u79fb\u52a8\u3001\u8d4b\u503c\u3001\u4ea4\u6362\u7b49\u64cd\u4f5c\u90fd\u662f\u9700\u8981\u7684\u3002\u5bf9\u5ba2\u6237\u6765\u8bf4\uff0c\u9664\u4e86\u4e24\u4e2a\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u76f8\u7b49\u6027\u5224\u5b9a\uff08\u7b14\u8005\u6700\u8fd1\u5728\u5c1d\u8bd5\u5b9e\u73b0\u8fd9\u4e2a\uff09\u4ee5\u5916\uff0c\u5176\u4ed6\u80fd\u60f3\u5230\u7684\u65b9\u6cd5\u5b83\u90fd\u6709\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_2\"><\/a>\u4e8c\u3001std::function\u7684\u5b9e\u73b0<\/h3>\n<p><span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u5b9e\u73b0\u4f4d\u4e8e\u00a0<span class=\"cnblogs_code\">&lt;functional&gt;<\/span>\u00a0\uff0c\u540e\u7eed\u7248\u672c\u8fc1\u79fb\u81f3\u4e86\u00a0<span class=\"cnblogs_code\">&lt;bits\/std_function.h&gt;<\/span>\u00a0\u3002\u4e0b\u9762\u8fd9\u6bb5\u4ee3\u7801\u662fGCC 4.8.1\uff08\u7b2c\u4e00\u4e2a\u652f\u6301\u5b8c\u6574C++11\u7684\u7248\u672c\uff09\u4e2d\u7684\u00a0<span class=\"cnblogs_code\">&lt;functional&gt;<\/span>\u00a0\u5934\u6587\u4ef6\uff0c\u51712579\u884c\uff0c\u9ed8\u8ba4\u6298\u53e0\uff0c\u614e\u5165\u3002<\/p>\n<div class=\"cnblogs_code\"><img decoding=\"async\" id=\"code_img_closed_4396106c-caf2-444c-ae3a-acfd11fdb239\" class=\"code_img_closed\" src=\"https:\/\/images.cnblogs.com\/OutliningIndicators\/ContractedBlock.gif\" alt=\"\" \/>\u00a0<span class=\"cnblogs_code_collapse\">functional<\/span><\/div>\n<p>\u8fd9\u4e2a\u5b9e\u73b0\u7684\u539f\u7406\u4e0e\u4e0a\u9762\u5206\u6790\u7684\u5927\u81f4\u76f8\u540c\uff0c\u4f7f\u7528\u51fd\u6570\u6307\u9488\u5b9e\u73b0\u591a\u6001\uff0c\u4e5f\u4f7f\u7528\u4e86small object optimization\u3002<\/p>\n<p>\u6ce8\uff1a\u6807\u51c6\u5e93\u7684\u6587\u4ef6\u7684\u7f29\u8fdb\u662f2\u683c\uff0c\u6709\u65f68\u4e2a\u7a7a\u683c\u4f1a\u7528\u4e00\u4e2atab\u4ee3\u66ff\uff0c\u5728\u5c06tab\u663e\u793a\u4e3a4\u5b57\u8282\u7684\u7f16\u8f91\u5668\u4e2d\u7f29\u8fdb\u4f1a\u6bd4\u8f83\u4e71\uff0c\u6211\u5df2\u7ecf\u628atab\u5168\u90e8\u66ff\u6362\u4e3a8\u4e2a\u7a7a\u683c\uff1b\u5f88\u591a\u4eba\u7f29\u8fdb\u4e60\u60ef\u662f4\u683c\uff0c\u4f46\u5982\u679c\u628a2\u683c\u5168\u90e8\u66ff\u6362\u62104\u683c\u4e5f\u4f1a\u4e71\u4e86\u683c\u5f0f\uff0c\u6240\u4ee5\u4ee5\u4e0b\u6458\u5f55\u81ea\u6807\u51c6\u5e93\u6587\u4ef6\u7684\u4ee3\u7801\u5168\u90e8\u90fd\u662f2\u683c\u7f29\u8fdb\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_2_1\"><\/a>2.1 \u7c7b\u578b\u7cfb\u7edf<\/h3>\n<p>\u7c7b\u578b\u4e4b\u95f4\u7684\u5173\u7cfb\uff0c\u65e0\u975e\u662f\u7ee7\u627f\u3001\u5d4c\u5957\u3001\u7ec4\u5408\u3002\u8fd9\u4e2a\u5b9e\u73b0\u4e2d\u4e09\u8005\u90fd\u6709\u3002<\/p>\n<p>\u5173\u4e8e\u7ee7\u627f\uff0c\u4f60\u4e5f\u8bb8\u4f1a\u95ee\uff0c\u6211\u4eec\u521a\u624d\u4e0d\u662f\u8bf4\u4e86\u8fd9\u79cd\u5b9e\u73b0\u6ca1\u6cd5\u7528\u7ee7\u627f\u5417\uff1f\u5b9e\u9645\u4e0a\u6ca1\u6709\u77db\u76fe\u3002\u521a\u624d\u8bf4\u7684\u7ee7\u627f\uff0c\u662f\u63a5\u53e3\u4e0a\u7684\u7ee7\u627f\uff0c\u8bb2\u5f97\u66f4\u5177\u4f53\u70b9\u5c31\u662f\u8981\u7ee7\u627f\u865a\u51fd\u6570\uff0c\u662f\u4e00\u79cdis-a\u7684\u5173\u7cfb\uff1b\u800c\u8fd9\u91cc\u7684\u7ee7\u627f\uff0c\u662f\u5b9e\u73b0\u4e0a\u7684\u7ee7\u627f\uff0c\u662f\u4e00\u79cdis-implemented-in-terms-of\u7684\u5173\u7cfb\uff0c\u5728\u8bed\u8a00\u5c42\u9762\u5927\u591a\u662fprivate\u7ee7\u627f\u3002<\/p>\n<p>\u5728\u6cdb\u578b\u7f16\u7a0b\u4e2d\uff0c\u8fd8\u6709\u4e00\u4e2a\u5173\u4e8e\u7ee7\u627f\u7684\u95ee\u9898\uff0c\u5c31\u662f\u5728\u7ee7\u627f\u4f53\u7cfb\u7684\u54ea\u4e00\u5c42\u5f15\u5165\u6a21\u677f\u53c2\u6570\u3002<\/p>\n<p>\u5d4c\u5957\uff0c\u5373\u7c7b\u4e2d\u5b9a\u4e49\u5d4c\u5957\u7c7b\u578b\uff0c\u4f7f\u7c7b\u4e4b\u95f4\u7684\u7ed3\u6784\u66f4\u52a0\u6e05\u6670\uff0c\u5728\u6cdb\u578b\u7f16\u7a0b\u4e2d\u8fd8\u53ef\u4ee5\u7b80\u5316\u8bbe\u8ba1\u3002<\/p>\n<p>\u7ec4\u5408\uff0c\u5728\u4e8e\u4e00\u4e2a\u7c7b\u7684\u5bf9\u8c61\u4e2d\u5305\u542b\u5176\u4ed6\u7c7b\u7684\u5bf9\u8c61\uff0c\u672c\u5e94\u5c5e\u4e8e\u5bf9\u8c61\u5173\u7cfb\u7684\u8303\u7574\uff0c\u4f46\u662f\u5728\u8fd9\u4e2a\u5b9e\u73b0\u4e2d\uff0c\u4e00\u4e2a\u7c7b\u4e00\u822c\u4e0d\u4f1a\u5728\u540c\u4e00\u4e2ascope\u5185\u51fa\u73b0\u591a\u4e2a\u5bf9\u8c61\uff0c\u56e0\u6b64\u6211\u8fd9\u91cc\u5c31\u76f4\u63a5\u628a\u5bf9\u8c61\u7ec4\u5408\u7684\u6982\u5ff5\u62ff\u6765\u7528\u4e86\u3002<\/p>\n<h4><a name=\"mark_2_1_1\"><\/a>2.1.1 \u5f02\u5e38\u7c7b<\/h4>\n<p>\u9996\u5148\u51fa\u73b0\u7684\u662f\u00a0<span class=\"cnblogs_code\">bad_function_call<\/span>\u00a0\u7c7b\u578b\uff0c\u8fd9\u662f\u4e00\u4e2a\u5f02\u5e38\u7c7b\uff0c\u5f53\u8c03\u7528\u7a7a\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5bf9\u8c61\u65f6\u629b\u51fa\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<pre>1 class bad_function_call : public std::exception\r\n2 {\r\n3 public:\r\n4   virtual ~bad_function_call() noexcept;\r\n5   const char* what() const noexcept;\r\n6 };<\/pre>\n<\/div>\n<p>\u7531\u4e8e\u4e0d\u662f\u6a21\u677f\u7c7b\uff08\u96be\u5f97\u80fd\u5728STL\u4e2d\u53d1\u73b0\u975e\u6a21\u677f\u7c7b\uff09\uff0c\u5b9e\u73b0\u88ab\u7f16\u8bd1\u597d\u653e\u5728\u4e86\u76ee\u6807\u6587\u4ef6\u4e2d\u3002\u867d\u7136GCC\u5f00\u6e90\uff0c\u4f46\u65e2\u7136\u8fd9\u4e2a\u7c7b\u4e0d\u592a\u91cd\u8981\uff0c\u800c\u4e14\u7a0d\u5fae\u60f3\u60f3\u5c31\u80fd\u77e5\u9053\u5b83\u662f\u600e\u4e48\u5b9e\u73b0\u7684\u4e86\uff0c\u6240\u4ee5\u8fd9\u91cc\u5c31\u4e0d\u6df1\u7a76\u4e86\u3002<\/p>\n<p>\u76f8\u5173\u7684\u8fd8\u6709\u4e00\u4e2a\u7528\u4e8e\u629b\u51fa\u5f02\u5e38\u7684\u51fd\u6570\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<pre>1 void __throw_bad_function_call() __attribute__((__noreturn__));<\/pre>\n<\/div>\n<p>\u5728\u00a0<span class=\"cnblogs_code\">&lt;bits\/functexcept.h&gt;<\/span>\u00a0\u4e2d\u3002\u540c\u6837\u53ea\u6709\u58f0\u660e\u6ca1\u6709\u5b9a\u4e49\u3002<\/p>\n<h4><a name=\"mark_2_1_2\"><\/a>2.1.2 \u6570\u636e\u5b58\u50a8<\/h4>\n<p>\u6709\u5173\u6570\u636e\u5b58\u50a8\u7684\u7c7b\u5171\u67093\u4e2a\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 class _Undefined_class;\r\n 2 \r\n 3 union _Nocopy_types\r\n 4 {\r\n 5   void*       _M_object;\r\n 6   const void* _M_const_object;\r\n 7   void (*_M_function_pointer)();\r\n 8   void (_Undefined_class::*_M_member_pointer)();\r\n 9 };\r\n10 \r\n11 union _Any_data\r\n12 {\r\n13   void*       _M_access()       { return &amp;_M_pod_data[0]; }\r\n14   const void* _M_access() const { return &amp;_M_pod_data[0]; }\r\n15 \r\n16   template&lt;typename _Tp&gt;\r\n17     _Tp&amp;\r\n18     _M_access()\r\n19     { return *static_cast&lt;_Tp*&gt;(_M_access()); }\r\n20 \r\n21   template&lt;typename _Tp&gt;\r\n22     const _Tp&amp;\r\n23     _M_access() const\r\n24     { return *static_cast&lt;const _Tp*&gt;(_M_access()); }\r\n25 \r\n26   _Nocopy_types _M_unused;\r\n27   char _M_pod_data[sizeof(_Nocopy_types)];\r\n28 };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">_Undefined_class<\/span>\u00a0\uff0c\u987e\u540d\u601d\u4e49\uff0c\u8fde\u5b9a\u4e49\u90fd\u6ca1\u6709\uff0c\u53ea\u662f\u7528\u4e8e\u58f0\u660e\u00a0<span class=\"cnblogs_code\">_Nocopy_types<\/span>\u00a0\u4e2d\u7684\u6210\u5458\u6307\u9488\u6570\u636e\u57df\uff0c\u56e0\u4e3a\u540c\u4e00\u4e2a\u5e73\u53f0\u4e0a\u6210\u5458\u6307\u9488\u7684\u5927\u5c0f\u662f\u76f8\u540c\u7684\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Nocopy_types<\/span>\u00a0\uff0c\u662f4\u79cd\u7c7b\u578b\u7684\u8054\u5408\u4f53\u7c7b\u578b\uff0c\u5206\u522b\u4e3a\u6307\u9488\u3001\u5e38\u91cf\u6307\u9488\u3001\u51fd\u6570\u6307\u9488\u4e0e\u6210\u5458\u6307\u9488\u3002\u201cnocopy\u201d\u6307\u7684\u662f\u8fd9\u51e0\u79cd\u7c7b\u578b\u6307\u5411\u7684\u5bf9\u8c61\u7c7b\u578b\uff0c\u800c\u4e0d\u662f\u672c\u8eab\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Any_data<\/span>\u00a0\uff0c\u662f\u4e24\u79cd\u7c7b\u578b\u7684\u8054\u5408\u4f53\u7c7b\u578b\uff0c\u4e00\u4e2a\u662f\u00a0<span class=\"cnblogs_code\">_Nocopy_types<\/span>\u00a0\uff0c\u53e6\u4e00\u4e2a\u662f\u00a0<span class=\"cnblogs_code\">char<\/span>\u00a0\u6570\u7ec4\uff0c\u4e24\u8005\u5927\u5c0f\u76f8\u7b49\u3002\u540e\u8005\u662fPOD\u7684\uff0cPOD\u7684\u597d\u5904\u591a\u554a\uff0cmemcpy\u53ef\u4ee5\u7528\uff0c\u6700\u91cd\u8981\u7684\u662f\u590d\u5236\u4e0d\u4f1a\u629b\u5f02\u5e38\u3002\u975e\u6a21\u677f\u00a0<span class=\"cnblogs_code\">_M_access()<\/span>\u00a0\u8fd4\u56de\u6307\u9488\uff0c\u6a21\u677f\u00a0<span class=\"cnblogs_code\">_M_access()<\/span>\u00a0\u8fd4\u56de\u89e3\u5f15\u7528\u7684\u7ed3\u679c\uff0c\u4e24\u8005\u90fd\u6709\u00a0<span class=\"cnblogs_code\">const<\/span>\u00a0\u91cd\u8f7d\u3002<\/p>\n<h4><a name=\"mark_2_1_3\"><\/a>2.1.3 \u8f85\u52a9\u7c7b<\/h4>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre>1 enum _Manager_operation\r\n2 {\r\n3   __get_type_info,\r\n4   __get_functor_ptr,\r\n5   __clone_functor,\r\n6   __destroy_functor\r\n7 };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">_Manager_operation<\/span>\u00a0\uff0c\u679a\u4e3e\u7c7b\uff0c\u662f\u524d\u9762\u6240\u8bf4\u63a7\u5236\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u51fd\u6570\u6307\u9488\u9700\u8981\u7684\u53c2\u6570\u7c7b\u578b\u3002\u5b9a\u4e49\u4e864\u79cd\u64cd\u4f5c\uff1a\u83b7\u5f97\u00a0<span class=\"cnblogs_code\">type_info<\/span>\u00a0\u3001\u83b7\u5f97\u4eff\u51fd\u6570\uff08\u5c31\u662f\u51fd\u6570\u5bf9\u8c61\uff09\u6307\u9488\u3001\u590d\u5236\u4eff\u51fd\u6570\u3001\u9500\u6bc1\uff08\u6790\u6784\uff09\u4eff\u51fd\u6570\u3002\u4ece\u8fd9\u4e2a\u5b9a\u4e49\u4e2d\u53ef\u4ee5\u770b\u51fa\uff0c<a href=\"https:\/\/www.cnblogs.com\/jerry-fuyi\/p\/std_function_interface_implementation.html#mark_1_4\" target=\"_blank\" rel=\"noopener noreferrer\">1.4<\/a>\u8282\u6240\u8bf4\u7684\u5404\u79cd\u529f\u80fd\u4e2d\uff0c\u9700\u8981\u5ef6\u8fdf\u8c03\u7528\u7684\uff0c\u9664\u4e86\u51fd\u6570\u5bf9\u8c61\u8c03\u7528\u4ee5\u5916\uff0c\u90fd\u53ef\u4ee5\u901a\u8fc7\u8fd94\u4e2a\u529f\u80fd\u6765\u7ec4\u5408\u8d77\u6765\u3002\u6211\u4eec\u540e\u9762\u8fd8\u4f1a\u8fdb\u4e00\u6b65\u63a2\u8ba8\u8fd9\u4e2a\u95ee\u9898\u3002<\/p>\n<div class=\"cnblogs_code\">\n<pre>1 template&lt;typename _Tp&gt;\r\n2   struct __is_location_invariant\r\n3   : integral_constant&lt;bool, (is_pointer&lt;_Tp&gt;::value\r\n4                              || is_member_pointer&lt;_Tp&gt;::value)&gt;\r\n5   { };<\/pre>\n<\/div>\n<p><span class=\"cnblogs_code\">__is_location_invariant<\/span>\u00a0\uff0c\u4e00\u4e2atrait\u7c7b\uff0c\u5224\u65ad\u4e00\u4e2a\u7c7b\u578b\u662f\u4e0d\u662f\u201c\u4f4d\u7f6e\u4e0d\u53d8\u201d\u7684\u3002\u4ece\u5b57\u9762\u4e0a\u6765\u7406\u89e3\uff0c\u4e00\u4e2a\u7c7b\u578b\u5982\u679c\u662f\u201c\u4f4d\u7f6e\u4e0d\u53d8\u201d\u7684\uff0c\u90a3\u4e48\u5bf9\u4e8e\u4e00\u4e2a\u8fd9\u79cd\u7c7b\u578b\u7684\u5bf9\u8c61\uff0c\u65e0\u8bba\u5b83\u590d\u5236\u5230\u54ea\u91cc\uff0c\u5404\u4e2a\u5bf9\u8c61\u7684\u5e95\u5c42\u8868\u793a\u90fd\u662f\u76f8\u540c\u7684\u3002\u5728\u8fd9\u4e2a\u5b9a\u4e49\u4e2d\uff0c\u4e00\u4e2a\u7c7b\u578b\u662f\u201c\u4f4d\u7f6e\u4e0d\u53d8\u201d\u7684\uff0c\u5f53\u4e14\u4ec5\u5f53\u5b83\u662f\u4e00\u4e2a\u6307\u9488\u6216\u6210\u5458\u6307\u9488\uff0c\u4e0e\u4e00\u822c\u7684\u7406\u89e3\u6709\u6240\u4e0d\u540c\uff08\u66f4\u65b0\uff1a\u540e\u6765\u6539\u4e3a\u00a0<span class=\"cnblogs_code\">template&lt;typename _Tp&gt;\u00a0struct\u00a0__is_location_invariant : is_trivially_copyable&lt;_Tp&gt;::type { };<\/span>\u00a0\uff0c\u8fd9\u5c31\u6bd4\u8f83\u5bb9\u6613\u7406\u89e3\u4e86\uff09\u3002<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Tp&gt;\r\n 2   struct _Simple_type_wrapper\r\n 3   {\r\n 4     _Simple_type_wrapper(_Tp __value) : __value(__value) { }\r\n 5 \r\n 6     _Tp __value;\r\n 7   };\r\n 8 \r\n 9 template&lt;typename _Tp&gt;\r\n10   struct __is_location_invariant&lt;_Simple_type_wrapper&lt;_Tp&gt; &gt;\r\n11   : __is_location_invariant&lt;_Tp&gt;\r\n12   { };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">_Simple_type_wrapper<\/span>\u00a0\uff0c\u4e00\u4e2a\u7b80\u5355\u7684\u5305\u88c5\u5668\uff0c\u7528\u4e8e\u907f\u514d\u00a0<span class=\"cnblogs_code\">void*<\/span>\u00a0\u4e0e\u6307\u9488\u7684\u6307\u9488\u4e4b\u95f4\u7c7b\u578b\u8f6c\u6362\u7684\u00a0<span class=\"cnblogs_code\">const<\/span>\u00a0\u95ee\u9898\u3002\u4ee5\u53ca\u00a0<span class=\"cnblogs_code\">__is_location_invariant<\/span>\u00a0\u5bf9\u00a0<span class=\"cnblogs_code\">_Simple_type_wrapper<\/span>\u00a0\u7684\u504f\u7279\u5316\u3002<\/p>\n<h4><a name=\"mark_2_1_4\"><\/a>2.1.4 \u5185\u5b58\u7ba1\u7406\u57fa\u7c7b<\/h4>\n<p>\u7c7b\u00a0<span class=\"cnblogs_code\">_Function_base<\/span>\u00a0\u5b9a\u4e49\u4e86\u4e00\u7cfb\u5217\u7528\u4e8e\u7ba1\u7406\u51fd\u6570\u5bf9\u8c61\u5185\u5b58\u7684\u51fd\u6570\uff0c\u8fd9\u662f\u4e00\u4e2a\u975e\u6a21\u677f\u7c7b\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 class _Function_base\r\n 2 {\r\n 3 public:\r\n 4   static const std::size_t _M_max_size = sizeof(_Nocopy_types);\r\n 5   static const std::size_t _M_max_align = __alignof__(_Nocopy_types);\r\n 6 \r\n 7   template&lt;typename _Functor&gt;\r\n 8     class _Base_manager;\r\n 9 \r\n10   template&lt;typename _Functor&gt;\r\n11     class _Ref_manager;\r\n12 \r\n13   _Function_base() : _M_manager(0) { }\r\n14 \r\n15   ~_Function_base()\r\n16   {\r\n17     if (_M_manager)\r\n18       _M_manager(_M_functor, _M_functor, __destroy_functor);\r\n19   }\r\n20 \r\n21   bool _M_empty() const { return !_M_manager; }\r\n22 \r\n23   typedef bool (*_Manager_type)(_Any_data&amp;, const _Any_data&amp;,\r\n24                                 _Manager_operation);\r\n25 \r\n26   _Any_data     _M_functor;\r\n27   _Manager_type _M_manager;\r\n28 };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">_Function_base<\/span>\u00a0\u662f\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u5b9e\u73b0\u57fa\u7c7b\uff0c\u5b9a\u4e49\u4e86\u4e24\u4e2a\u9759\u6001\u5e38\u91cf\uff0c\u7528\u4e8e\u540e\u9762\u7684trait\u7c7b\uff1b\u4e24\u4e2a\u5185\u90e8\u7c7b\uff0c\u7528\u4e8e\u5305\u88c5\u9759\u6001\u65b9\u6cd5\uff1b\u51fd\u6570\u6307\u9488\u7c7b\u578b\u00a0<span class=\"cnblogs_code\">_Manager_type<\/span>\u00a0\u7684\u5bf9\u8c61\u00a0<span class=\"cnblogs_code\">_M_manager<\/span>\u00a0\uff0c\u7528\u4e8e\u5b58\u53d6\u00a0<span class=\"cnblogs_code\">_Any_data<\/span>\u00a0\u7c7b\u578b\u7684\u00a0<span class=\"cnblogs_code\">_M_functor<\/span>\u00a0\u4e2d\u7684\u6570\u636e\uff1b\u6784\u9020\u51fd\u6570\uff0c\u5c06\u51fd\u6570\u6307\u9488\u7f6e\u4e3a\u7a7a\uff1b\u6790\u6784\u51fd\u6570\uff0c\u8c03\u7528\u51fd\u6570\u6307\u9488\uff0c\u9500\u6bc1\u51fd\u6570\u5bf9\u8c61\uff1b<span class=\"cnblogs_code\">_M_empty()<\/span>\u00a0\u65b9\u6cd5\uff0c\u68c0\u6d4b\u5185\u90e8\u662f\u5426\u5b58\u6709\u51fd\u6570\u5bf9\u8c61\u3002<\/p>\n<p>\u6211\u4eec\u6765\u770b\u5176\u4e2d\u7684\u00a0<span class=\"cnblogs_code\">_Base_manager<\/span>\u00a0\u7c7b\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   class _Base_manager\r\n 3   {\r\n 4   protected:\r\n 5     static const bool __stored_locally =\r\n 6     (__is_location_invariant&lt;_Functor&gt;::value\r\n 7      &amp;&amp; sizeof(_Functor) &lt;= _M_max_size\r\n 8      &amp;&amp; __alignof__(_Functor) &lt;= _M_max_align\r\n 9      &amp;&amp; (_M_max_align % __alignof__(_Functor) == 0));\r\n10 \r\n11     typedef integral_constant&lt;bool, __stored_locally&gt; _Local_storage;\r\n12 \r\n13     static _Functor*\r\n14     _M_get_pointer(const _Any_data&amp; __source);\r\n15 \r\n16     static void\r\n17     _M_clone(_Any_data&amp; __dest, const _Any_data&amp; __source, true_type);\r\n18 \r\n19     static void\r\n20     _M_clone(_Any_data&amp; __dest, const _Any_data&amp; __source, false_type);\r\n21 \r\n22     static void\r\n23     _M_destroy(_Any_data&amp; __victim, true_type);\r\n24 \r\n25     static void\r\n26     _M_destroy(_Any_data&amp; __victim, false_type);\r\n27 \r\n28   public:\r\n29     static bool\r\n30     _M_manager(_Any_data&amp; __dest, const _Any_data&amp; __source,\r\n31                _Manager_operation __op);\r\n32 \r\n33     static void\r\n34     _M_init_functor(_Any_data&amp; __functor, _Functor&amp;&amp; __f);\r\n35 \r\n36     template&lt;typename _Signature&gt;\r\n37       static bool\r\n38       _M_not_empty_function(const function&lt;_Signature&gt;&amp; __f);\r\n39 \r\n40     template&lt;typename _Tp&gt;\r\n41       static bool\r\n42       _M_not_empty_function(const _Tp*&amp; __fp);\r\n43 \r\n44     template&lt;typename _Class, typename _Tp&gt;\r\n45       static bool\r\n46       _M_not_empty_function(_Tp _Class::* const&amp; __mp);\r\n47 \r\n48     template&lt;typename _Tp&gt;\r\n49       static bool\r\n50       _M_not_empty_function(const _Tp&amp;);\r\n51 \r\n52   private:\r\n53     static void\r\n54     _M_init_functor(_Any_data&amp; __functor, _Functor&amp;&amp; __f, true_type);\r\n55 \r\n56     static void\r\n57     _M_init_functor(_Any_data&amp; __functor, _Functor&amp;&amp; __f, false_type);\r\n58   };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u5b9a\u4e49\u4e86\u4e00\u4e2a\u9759\u6001\u5e03\u5c14\u5e38\u91cf\u00a0<span class=\"cnblogs_code\">__stored_locally<\/span>\u00a0\uff0c\u5b83\u4e3a\u771f\u5f53\u4e14\u4ec5\u5f53\u00a0<span class=\"cnblogs_code\">__is_location_invariant<\/span>\u00a0trait\u4e3a\u771f\u3001\u4eff\u51fd\u6570\u653e\u5f97\u4e0b\u3001\u4eff\u51fd\u6570\u7684align\u7b26\u5408\u4e24\u4e2a\u8981\u6c42\u3002\u7136\u540e\u518d\u53cd\u8fc7\u6765\u6839\u636e\u8fd9\u4e2a\u503c\u5b9a\u4e49trait\u7c7b\u00a0<span class=\"cnblogs_code\">_Local_storage<\/span>\u00a0\uff08\u6807\u51c6\u5e93\u91cc\u4e00\u822c\u90fd\u662f\u6839\u636evalue trait\u6765\u751f\u6210value\uff09\u3002<\/p>\n<p>\u5176\u4f59\u51e0\u4e2a\u9759\u6001\u65b9\u6cd5\uff0c\u987e\u540d\u601d\u4e49\u5373\u53ef\u3002\u6709\u4e2a\u503c\u5f97\u601d\u8003\u7684\u95ee\u9898\uff0c\u5c31\u662f\u4e3a\u4ec0\u4e48\u00a0<span class=\"cnblogs_code\">_M_init_functor<\/span>\u00a0\u662fpublic\u7684\uff0c\u6ca1\u6709\u88ab\u653e\u8fdb\u00a0<span class=\"cnblogs_code\">_M_manager<\/span>\u00a0\u5462\uff1f<\/p>\n<p>\u518d\u6765\u770b\u00a0<span class=\"cnblogs_code\">_Ref_manager<\/span>\u00a0\u7c7b\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   class _Ref_manager : public _Base_manager&lt;_Functor*&gt;\r\n 3   {\r\n 4     typedef _Function_base::_Base_manager&lt;_Functor*&gt; _Base;\r\n 5 \r\n 6   public:\r\n 7     static bool\r\n 8     _M_manager(_Any_data&amp; __dest, const _Any_data&amp; __source,\r\n 9                _Manager_operation __op);\r\n10 \r\n11     static void\r\n12     _M_init_functor(_Any_data&amp; __functor, reference_wrapper&lt;_Functor&gt; __f);\r\n13   };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">_Ref_manager<\/span>\u00a0\u7ee7\u627f\u81ea\u00a0<span class=\"cnblogs_code\">_Base_manager<\/span>\u00a0\u7c7b\uff0c\u8986\u5199\u4e86\u4e24\u4e2a\u9759\u6001\u65b9\u6cd5\u3002<\/p>\n<h4><a name=\"mark_2_1_5\"><\/a>2.1.5 \u4eff\u51fd\u6570\u8c03\u7528<\/h4>\n<p>\u8d77\u8f85\u52a9\u4f5c\u7528\u7684\u6a21\u677f\u51fd\u6570\u00a0<span class=\"cnblogs_code\">__callable_functor<\/span>\u00a0\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   inline _Functor&amp;\r\n 3   __callable_functor(_Functor&amp; __f)\r\n 4   { return __f; }\r\n 5 \r\n 6 template&lt;typename _Member, typename _Class&gt;\r\n 7   inline _Mem_fn&lt;_Member _Class::*&gt;\r\n 8   __callable_functor(_Member _Class::* &amp;__p)\r\n 9   { return std::mem_fn(__p); }\r\n10 \r\n11 template&lt;typename _Member, typename _Class&gt;\r\n12   inline _Mem_fn&lt;_Member _Class::*&gt;\r\n13   __callable_functor(_Member _Class::* const &amp;__p)\r\n14   { return std::mem_fn(__p); }\r\n15 \r\n16 template&lt;typename _Member, typename _Class&gt;\r\n17   inline _Mem_fn&lt;_Member _Class::*&gt;\r\n18   __callable_functor(_Member _Class::* volatile &amp;__p)\r\n19   { return std::mem_fn(__p); }\r\n20 \r\n21 template&lt;typename _Member, typename _Class&gt;\r\n22   inline _Mem_fn&lt;_Member _Class::*&gt;\r\n23   __callable_functor(_Member _Class::* const volatile &amp;__p)\r\n24   { return std::mem_fn(__p); }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u5bf9\u975e\u6210\u5458\u6307\u9488\u7c7b\u578b\uff0c\u76f4\u63a5\u8fd4\u56de\u53c2\u6570\u672c\u8eab\uff1b\u5bf9\u6210\u5458\u6307\u9488\u7c7b\u578b\uff0c\u8fd4\u56de\u00a0<span class=\"cnblogs_code\">mem_fn()<\/span>\u00a0\u7684\u7ed3\u679c\uff08\u5c06\u7c7b\u5bf9\u8c61\u8f6c\u6362\u4e3a\u7b2c\u4e00\u4e2a\u53c2\u6570\uff1b\u8fd9\u4e2a\u6807\u51c6\u5e93\u51fd\u6570\u7684\u5b9e\u73b0\u4e0d\u5728\u8fd9\u7bc7\u6587\u7ae0\u4e2d\u6d89\u53ca\uff09\uff0c\u5e76\u6709cv-qualified\u91cd\u8f7d\u3002\u5b83\u6539\u53d8\u4e86\u8c03\u7528\u7684\u5f62\u5f0f\uff0c\u628a\u6240\u6709\u7684\u53c2\u6570\u90fd\u653e\u5728\u4e86\u5c0f\u62ec\u53f7\u4e2d\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Function_handler<\/span>\u00a0\u7c7b\uff0c\u7ba1\u7406\u4eff\u51fd\u6570\u8c03\u7528\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Signature, typename _Functor&gt;\r\n 2   class _Function_handler;\r\n 3 \r\n 4 template&lt;typename _Res, typename _Functor, typename... _ArgTypes&gt;\r\n 5   class _Function_handler&lt;_Res(_ArgTypes...), _Functor&gt;\r\n 6   : public _Function_base::_Base_manager&lt;_Functor&gt;\r\n 7   {\r\n 8     typedef _Function_base::_Base_manager&lt;_Functor&gt; _Base;\r\n 9 \r\n10   public:\r\n11     static _Res\r\n12     _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args);\r\n13   };\r\n14 \r\n15 template&lt;typename _Functor, typename... _ArgTypes&gt;\r\n16   class _Function_handler&lt;void(_ArgTypes...), _Functor&gt;\r\n17   : public _Function_base::_Base_manager&lt;_Functor&gt;\r\n18   {\r\n19     typedef _Function_base::_Base_manager&lt;_Functor&gt; _Base;\r\n20 \r\n21    public:\r\n22     static void\r\n23     _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args);\r\n24   };\r\n25 \r\n26 template&lt;typename _Res, typename _Functor, typename... _ArgTypes&gt;\r\n27   class _Function_handler&lt;_Res(_ArgTypes...), reference_wrapper&lt;_Functor&gt; &gt;\r\n28   : public _Function_base::_Ref_manager&lt;_Functor&gt;\r\n29   {\r\n30     typedef _Function_base::_Ref_manager&lt;_Functor&gt; _Base;\r\n31 \r\n32    public:\r\n33     static _Res\r\n34     _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args);\r\n35   };\r\n36 \r\n37 template&lt;typename _Functor, typename... _ArgTypes&gt;\r\n38   class _Function_handler&lt;void(_ArgTypes...), reference_wrapper&lt;_Functor&gt; &gt;\r\n39   : public _Function_base::_Ref_manager&lt;_Functor&gt;\r\n40   {\r\n41     typedef _Function_base::_Ref_manager&lt;_Functor&gt; _Base;\r\n42 \r\n43    public:\r\n44     static void\r\n45     _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args);\r\n46   };\r\n47 \r\n48 template&lt;typename _Class, typename _Member, typename _Res,\r\n49          typename... _ArgTypes&gt;\r\n50   class _Function_handler&lt;_Res(_ArgTypes...), _Member _Class::*&gt;\r\n51   : public _Function_handler&lt;void(_ArgTypes...), _Member _Class::*&gt;\r\n52   {\r\n53     typedef _Function_handler&lt;void(_ArgTypes...), _Member _Class::*&gt;\r\n54       _Base;\r\n55 \r\n56    public:\r\n57     static _Res\r\n58     _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args);\r\n59   };\r\n60 \r\n61 template&lt;typename _Class, typename _Member, typename... _ArgTypes&gt;\r\n62   class _Function_handler&lt;void(_ArgTypes...), _Member _Class::*&gt;\r\n63   : public _Function_base::_Base_manager&lt;\r\n64                _Simple_type_wrapper&lt; _Member _Class::* &gt; &gt;\r\n65   {\r\n66     typedef _Member _Class::* _Functor;\r\n67     typedef _Simple_type_wrapper&lt;_Functor&gt; _Wrapper;\r\n68     typedef _Function_base::_Base_manager&lt;_Wrapper&gt; _Base;\r\n69 \r\n70   public:\r\n71     static bool\r\n72     _M_manager(_Any_data&amp; __dest, const _Any_data&amp; __source,\r\n73                _Manager_operation __op);\r\n74 \r\n75     static void\r\n76     _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args);\r\n77   };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u5171\u67096\u4e2a\u7279\u5316\u7248\u672c\uff1a\u8fd4\u56de\u503c\u7c7b\u578b\u4e3a\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u3001\u5176\u4ed6\uff1b\u51fd\u6570\u5bf9\u8c61\u7c7b\u578b\u4e3a\u00a0<span class=\"cnblogs_code\">std::reference_wrapper<\/span>\u00a0\u3001\u6210\u5458\u6307\u9488\u3001\u5176\u4ed6\u3002<\/p>\n<p>\u7ee7\u627f\u81ea\u00a0<span class=\"cnblogs_code\">_Function_base::_Base_manager<\/span>\u00a0\u6216\u00a0<span class=\"cnblogs_code\">_Function_base::_Ref_manager<\/span>\u00a0\uff0c\u63d0\u4f9b\u4e86\u9759\u6001\u65b9\u6cd5\u00a0<span class=\"cnblogs_code\">_M_invoke()<\/span>\u00a0\uff0c\u7528\u4e8e\u4eff\u51fd\u6570\u8c03\u7528\u3002\u6709\u4e00\u4e2a\u8986\u5199\u7684\u00a0<span class=\"cnblogs_code\">_M_manager()<\/span>\u00a0\uff0c\u8868\u9762\u4e0a\u770b\u662f\u4e00\u4e2a\u504f\u7279\u5316\u6709\u8986\u5199\uff0c\u5b9e\u9645\u4e0a\u662f\u4e24\u4e2a\uff0c\u56e0\u4e3a\u8fd4\u56de\u975e\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u7684\u6210\u5458\u6307\u9488\u504f\u7279\u5316\u7248\u672c\u8fd8\u7ee7\u627f\u4e86\u5176\u5bf9\u5e94\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u504f\u7279\u5316\u7248\u672c\u3002<\/p>\n<h4><a name=\"mark_2_1_6\"><\/a>2.1.6 \u63a5\u53e3\u5b9a\u4e49<\/h4>\n<p>\u7ec8\u4e8e\u56de\u5230\u4f1f\u5927\u7684\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u4e86\uff0c\u4f46\u662f\u6211\u4eec\u8fd8\u5f97\u518d\u770b\u70b9\u522b\u7684\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Arg, typename _Result&gt;\r\n 2   struct unary_function\r\n 3   {\r\n 4     typedef _Arg     argument_type;   \r\n 5 \r\n 6     typedef _Result     result_type;  \r\n 7   };\r\n 8 \r\n 9 template&lt;typename _Arg1, typename _Arg2, typename _Result&gt;\r\n10   struct binary_function\r\n11   {\r\n12     typedef _Arg1     first_argument_type; \r\n13 \r\n14     typedef _Arg2     second_argument_type;\r\n15 \r\n16     typedef _Result     result_type;\r\n17   };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">std::unary_function<\/span>\u00a0\u4e0e\u00a0<span class=\"cnblogs_code\">std::binary_function<\/span>\u00a0\uff0c\u5b9a\u4e49\u4e86\u4e00\u5143\u548c\u4e8c\u5143\u51fd\u6570\u7684\u53c2\u6570\u7c7b\u578b\u4e0e\u8fd4\u56de\u503c\u7c7b\u578b\u3002<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 2   struct _Maybe_unary_or_binary_function { };\r\n 3 \r\n 4 template&lt;typename _Res, typename _T1&gt;\r\n 5   struct _Maybe_unary_or_binary_function&lt;_Res, _T1&gt;\r\n 6   : std::unary_function&lt;_T1, _Res&gt; { };\r\n 7 \r\n 8 template&lt;typename _Res, typename _T1, typename _T2&gt;\r\n 9   struct _Maybe_unary_or_binary_function&lt;_Res, _T1, _T2&gt;\r\n10   : std::binary_function&lt;_T1, _T2, _Res&gt; { };<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">_Maybe_unary_or_binary_function<\/span>\u00a0\u7c7b\uff0c\u5f53\u6a21\u677f\u53c2\u6570\u8868\u793a\u7684\u51fd\u6570\u4e3a\u4e00\u5143\u6216\u4e8c\u5143\u65f6\uff0c\u5206\u522b\u7ee7\u627f\u00a0<span class=\"cnblogs_code\">std::unary_function<\/span>\u00a0\u4e0e\u00a0<span class=\"cnblogs_code\">std::binary_function<\/span>\u00a0\u3002<\/p>\n<p>\u73b0\u5728\u53ef\u4ee5\u7ed9\u51fa\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7c7b\u5b9a\u4e49\u4e0e\u65b9\u6cd5\u58f0\u660e\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre>  1 template&lt;typename _Signature&gt;\r\n  2   class function;\r\n  3 \r\n  4 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n  5   class function&lt;_Res(_ArgTypes...)&gt;\r\n  6   : public _Maybe_unary_or_binary_function&lt;_Res, _ArgTypes...&gt;,\r\n  7     private _Function_base\r\n  8   {\r\n  9     typedef _Res _Signature_type(_ArgTypes...);\r\n 10 \r\n 11     template&lt;typename _Functor&gt;\r\n 12       using _Invoke = decltype(__callable_functor(std::declval&lt;_Functor&amp;&gt;())\r\n 13                                (std::declval&lt;_ArgTypes&gt;()...) );\r\n 14 \r\n 15     template&lt;typename _CallRes, typename _Res1&gt;\r\n 16       struct _CheckResult\r\n 17       : is_convertible&lt;_CallRes, _Res1&gt; { };\r\n 18 \r\n 19     template&lt;typename _CallRes&gt;\r\n 20       struct _CheckResult&lt;_CallRes, void&gt;\r\n 21       : true_type { };\r\n 22 \r\n 23     template&lt;typename _Functor&gt;\r\n 24       using _Callable = _CheckResult&lt;_Invoke&lt;_Functor&gt;, _Res&gt;;\r\n 25 \r\n 26     template&lt;typename _Cond, typename _Tp&gt;\r\n 27       using _Requires = typename enable_if&lt;_Cond::value, _Tp&gt;::type;\r\n 28 \r\n 29   public:\r\n 30     typedef _Res result_type;\r\n 31 \r\n 32     function() noexcept;\r\n 33 \r\n 34     function(nullptr_t) noexcept;\r\n 35 \r\n 36     function(const function&amp; __x);\r\n 37 \r\n 38     function(function&amp;&amp; __x);\r\n 39 \r\n 40     \/\/ TODO: needs allocator_arg_t\r\n 41 \r\n 42     template&lt;typename _Functor,\r\n 43              typename = _Requires&lt;_Callable&lt;_Functor&gt;, void&gt;&gt;\r\n 44       function(_Functor);\r\n 45 \r\n 46     function&amp;\r\n 47     operator=(const function&amp; __x);\r\n 48 \r\n 49     function&amp;\r\n 50     operator=(function&amp;&amp; __x);\r\n 51 \r\n 52     function&amp;\r\n 53     operator=(nullptr_t);\r\n 54 \r\n 55     template&lt;typename _Functor&gt;\r\n 56       _Requires&lt;_Callable&lt;_Functor&gt;, function&amp;&gt;\r\n 57       operator=(_Functor&amp;&amp; __f);\r\n 58 \r\n 59     template&lt;typename _Functor&gt;\r\n 60       function&amp;\r\n 61       operator=(reference_wrapper&lt;_Functor&gt; __f) noexcept;\r\n 62     void swap(function&amp; __x);\r\n 63 \r\n 64     \/\/ TODO: needs allocator_arg_t\r\n 65     \/*\r\n 66     template&lt;typename _Functor, typename _Alloc&gt;\r\n 67       void\r\n 68       assign(_Functor&amp;&amp; __f, const _Alloc&amp; __a);\r\n 69     *\/\r\n 70 \r\n 71     explicit operator bool() const noexcept;\r\n 72 \r\n 73     _Res operator()(_ArgTypes... __args) const;\r\n 74 \r\n 75 #ifdef __GXX_RTTI\r\n 76     const type_info&amp; target_type() const noexcept;\r\n 77 \r\n 78     template&lt;typename _Functor&gt;       _Functor* target() noexcept;\r\n 79 \r\n 80     template&lt;typename _Functor&gt; const _Functor* target() const noexcept;\r\n 81 #endif\r\n 82 \r\n 83   private:\r\n 84     typedef _Res (*_Invoker_type)(const _Any_data&amp;, _ArgTypes...);\r\n 85     _Invoker_type _M_invoker;\r\n 86 };\r\n 87 \r\n 88 template&lt;typename _Res, typename... _Args&gt;\r\n 89   inline bool\r\n 90   operator==(const function&lt;_Res(_Args...)&gt;&amp; __f, nullptr_t) noexcept;\r\n 91 \r\n 92 template&lt;typename _Res, typename... _Args&gt;\r\n 93   inline bool\r\n 94   operator==(nullptr_t, const function&lt;_Res(_Args...)&gt;&amp; __f) noexcept;\r\n 95 \r\n 96 template&lt;typename _Res, typename... _Args&gt;\r\n 97   inline bool\r\n 98   operator!=(const function&lt;_Res(_Args...)&gt;&amp; __f, nullptr_t) noexcept;\r\n 99 \r\n100 template&lt;typename _Res, typename... _Args&gt;\r\n101   inline bool\r\n102   operator!=(nullptr_t, const function&lt;_Res(_Args...)&gt;&amp; __f) noexcept;\r\n103 \r\n104 template&lt;typename _Res, typename... _Args&gt;\r\n105   inline void\r\n106   swap(function&lt;_Res(_Args...)&gt;&amp; __x, function&lt;_Res(_Args...)&gt;&amp; __y);<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u524d\u9762\u8bf4\u8fc7\uff0c<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7c7b\u7684\u6a21\u677f\u53c2\u6570\u662f\u4e00\u4e2a\u51fd\u6570\u7c7b\u578b\u3002\u4e00\u4e2a\u51fd\u6570\u7c7b\u578b\u4e5f\u662f\u4e00\u4e2a\u7c7b\u578b\uff1b<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u53ea\u5728\u6a21\u677f\u53c2\u6570\u662f\u51fd\u6570\u7c7b\u578b\u65f6\u624d\u6709\u610f\u4e49\uff1b\u56e0\u6b64\uff0c\u6709\u7528\u7684\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u662f\u4e00\u4e2a\u7279\u5316\u7684\u6a21\u677f\uff0c\u9700\u8981\u4e00\u4e2a\u58f0\u660e\u3002\u6807\u51c6\u5e93\u89c4\u5b9a\u6ca1\u6709\u7279\u5316\u7684\u58f0\u660e\u662f\u6ca1\u6709\u5b9a\u4e49\u7684\u3002<\/p>\n<p><span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7ee7\u627f\u81ea\u4e24\u4e2a\u7c7b\uff1a\u516c\u6709\u7ee7\u627f\u6a21\u677f\u7c7b\u00a0<span class=\"cnblogs_code\">_Maybe_unary_or_binary_function<\/span>\u00a0\uff0c\u79c1\u6709\u7ee7\u627f\u975e\u6a21\u677f\u7c7b\u00a0<span class=\"cnblogs_code\">_Function_base<\/span>\u00a0\u3002<\/p>\n<p>\u524d\u8005\u662f\u516c\u6709\u7ee7\u627f\uff0c\u4f46\u5b9e\u9645\u4e0a\u6ca1\u6709\u7ee7\u627f\u865a\u51fd\u6570\uff0c\u4e0d\u5c5e\u4e8e\u63a5\u53e3\u7ee7\u627f\uff0c\u800c\u662f\u5b9e\u73b0\u7ee7\u627f\uff0c\u7ee7\u627f\u7684\u662f\u57fa\u7c7b\u5b9a\u4e49\u7684\u7c7b\u578b\u522b\u540d\u3002\u56e0\u4e3a\u8fd9\u4e9b\u7c7b\u578b\u522b\u540d\u662f\u9762\u5411\u5ba2\u6237\u7684\uff0c\u6240\u4ee5\u5fc5\u987b\u516c\u6709\u7ee7\u627f\u3002\u8fd9\u4e2a\u7ee7\u627f\u4f7f\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5728\u4e0d\u540c\u6570\u91cf\u7684\u6a21\u677f\u53c2\u6570\u7684\u5b9e\u4f8b\u5316\u4e0b\u5b9a\u4e49\u4e0d\u540c\u7684\u7c7b\u578b\u522b\u540d\u3002\u7ee7\u627f\u662f\u5b9e\u73b0\u8fd9\u79cd\u529f\u80fd\u7684\u552f\u4e00\u65b9\u6cd5\uff0cSFINAE\u4e0d\u884c\u3002\uff08\u8fd9\u662f\u672c\u6587\u7b2c\u4e00\u6b21\u51fa\u73b0SFINAE\u8fd9\u4e2a\u8bcd\uff0c\u6211\u9ed8\u8ba4\u4f60\u770b\u5f97\u61c2\u3002\u8fd9\u662f\u6cdb\u578b\u7f16\u7a0b\u4e2d\u7684\u5e38\u7528\u6280\u5de7\uff0c\u5982\u679c\u4e0d\u4f1a\u8bf7\u53c2\u8003<a title=\"C++\u5947\u6deb\u5de7\u6280\u4e4bSFINAE\" href=\"https:\/\/www.jianshu.com\/p\/45a2410d4085\" target=\"_blank\" rel=\"noopener noreferrer\">\u8fd9\u7bc7\u6587\u7ae0<\/a>\u6216Google\u3002\uff09<\/p>\n<p>\u540e\u8005\u662f\u79c1\u6709\u7ee7\u627f\uff0c\u4e5f\u5c5e\u4e8e\u5b9e\u73b0\u7ee7\u627f\uff0c\u7ee7\u627f\u4e86\u57fa\u7c7b\u7684\u4e24\u4e2a\u6570\u636e\u57df\u4e0e\u51e0\u4e2a\u9759\u6001\u65b9\u6cd5\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Signature_type<\/span>\u00a0\u662f\u4e00\u4e2a\u7c7b\u578b\u522b\u540d\uff0c\u5c31\u662f\u6a21\u677f\u53c2\u6570\uff0c\u662f\u4e00\u4e2a\u51fd\u6570\u7c7b\u578b\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Invoke<\/span>\u00a0\u662f\u4e00\u4e2a\u522b\u540d\u6a21\u677f\uff0c\u5c31\u662f\u4eff\u51fd\u6570\u88ab\u6309\u53c2\u6570\u7c7b\u578b\u8c03\u7528\u7684\u8fd4\u56de\u7c7b\u578b\u3002\u5982\u679c\u4e0d\u80fd\u8c03\u7528\uff0c\u6839\u636eSFINAE\uff0cS\u9519\u8bef\u4e0d\u4f1aE\uff0c\u4f46\u8fd9\u4e2a\u522b\u540d\u53ea\u6709\u4e00\u4e2a\u5b9a\u4e49\uff0c\u5728\u4f7f\u7528\u7684\u5730\u65b9\u6240\u6709S\u90fdE\u4e86\uff0c\u7f16\u8bd1\u5668\u8fd8\u662f\u4f1a\u7ed9E\u3002<\/p>\n<p><span class=\"cnblogs_code\">_CheckResult<\/span>\u00a0\u662f\u4e00\u4e2atrait\u7c7b\uff0c\u68c0\u6d4b\u7b2c\u4e00\u4e2a\u6a21\u677f\u53c2\u6570\u80fd\u5426\u8f6c\u6362\u4e3a\u7b2c\u4e8c\u4e2a\u3002\u53e6\u6709\u7b2c\u4e8c\u4e2a\u53c2\u6570\u4e3a\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u7684\u504f\u7279\u5316\uff0c\u5728\u7c7b\u578b\u68c0\u6d4b\u4e0a\u4f7f\u8fd4\u56de\u7c7b\u578b\u4e3a\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u7684\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5bf9\u8c61\u80fd\u652f\u6301\u4efb\u4f55\u8fd4\u56de\u503c\u7684\u51fd\u6570\u5bf9\u8c61\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Callable<\/span>\u00a0\u4e5f\u662f\u4e00\u4e2atrait\u7c7b\uff0c\u5229\u7528\u4e0a\u9762\u4e24\u4e2a\u5b9a\u4e49\u68c0\u6d4b\u4eff\u51fd\u6570\u7c7b\u578b\u4e0e\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u6a21\u677f\u53c2\u6570\u662f\u5426\u5339\u914d\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Requires<\/span>\u00a0\u662f\u4e00\u4e2a\u6709\u8da3\u7684\u522b\u540d\u6a21\u677f\uff0c\u5982\u679c\u6a21\u677f\u53c2\u6570\u4e2d\u7b2c\u4e00\u4e2avalue trait\u4e3a\u00a0<span class=\"cnblogs_code\">true<\/span>\u00a0\uff0c\u5219\u5b9a\u4e49\u4e3a\u7b2c\u4e8c\u4e2a\u6a21\u677f\u53c2\u6570\uff0c\u5426\u5219\u672a\u5b9a\u4e49\uff08\u662f\u6ca1\u6709\uff0c\u4e0d\u662f\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\uff09\uff0c\u4f7f\u7528\u65f6\u5c06\u4ea4\u7ed9SFINAE\u5904\u7406\u3002\u5b83\u5927\u81f4\u4e0a\u5b9e\u73b0\u4e86C++20\u4e2d\u00a0<span class=\"cnblogs_code\">require<\/span>\u00a0\u5173\u952e\u5b57\u7684\u529f\u80fd\u3002\u5b9e\u9645\u4e0aconcept\u57282005\u5e74\u5c31\u6709proposal\u4e86\uff0c\u4e00\u8def\u4eceC++0x\u62d6\u5230C++20\u3002\u6211\u8ba1\u5212\u5728C++20\u6807\u51c6\u6b63\u5f0f\u53d1\u5e03\u4e4b\u524d\u5199\u4e00\u7bc7\u6587\u7ae0\u5b8c\u6574\u4ecb\u7ecdconcept\u3002<\/p>\n<p><span class=\"cnblogs_code\">result_type<\/span>\u00a0\u662f\u6a21\u677f\u53c2\u6570\u51fd\u6570\u7c7b\u578b\u7684\u8fd4\u56de\u503c\u7c7b\u578b\uff0c\u4e0e\u57fa\u7c7b\u4e2d\u5b9a\u4e49\u7684\u76f8\u540c\u3002<\/p>\n<p>\u5728\u7c7b\u5b9a\u4e49\u6700\u540e\u7684\u79c1\u6709\u6bb5\uff0c\u8fd8\u5b9a\u4e49\u4e86\u4e00\u4e2a\u51fd\u6570\u6307\u9488\u7c7b\u578b\u4ee5\u53ca\u8be5\u7c7b\u578b\u7684\u4e00\u4e2a\u5bf9\u8c61\uff0c\u8fd9\u662f\u7b2c\u4e8c\u4e2a\u51fd\u6570\u6307\u9488\u3002<\/p>\n<p>\u5176\u4f59\u7684\u5404\u79cd\u51fd\u6570\uff0c\u5728<a href=\"https:\/\/www.cnblogs.com\/jerry-fuyi\/p\/std_function_interface_implementation.html#mark_1_4\" target=\"_blank\" rel=\"noopener noreferrer\">1.4<\/a>\u8282\u90fd\u4ecb\u7ecd\u8fc7\u4e86\u3002<\/p>\n<h4><a name=\"mark_2_1_7\"><\/a>2.1.7 \u7c7b\u578b\u5173\u7cfb<\/h4>\n<p>\u8bb2\u4e86\u8fd9\u4e48\u591a\u7c7b\u578b\uff0c\u4f60\u8bb0\u4f4f\u5b83\u4eec\u4e4b\u95f4\u7684\u5173\u7cfb\u4e86\u5417\uff1f\u6211\u4eec\u518d\u6765\u81ea\u9876\u5411\u4e0b\u5730\u68b3\u7406\u4e00\u904d\u3002<\/p>\n<p>\u4e00\u4e2a\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5bf9\u8c61\u4e2d\u5305\u542b\u4e00\u4e2a\u51fd\u6570\u6307\u9488\uff0c\u5b83\u4f1a\u88ab\u521d\u59cb\u5316\u4e3a\u00a0<span class=\"cnblogs_code\">_Function_handler<\/span>\u00a0\u7c7b\u4e2d\u7684\u9759\u6001\u51fd\u6570\u7684\u6307\u9488\u3002<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u4e0e\u00a0<span class=\"cnblogs_code\">_Function_handler<\/span>\u00a0\u7c7b\u4e4b\u95f4\uff0c\u53ef\u4ee5\u8ba4\u4e3a\u662f\u7ec4\u5408\u5173\u7cfb\u3002<\/p>\n<p><span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7ee7\u627f\u81ea\u00a0<span class=\"cnblogs_code\">_Maybe_unary_or_binary_function<\/span>\u00a0\u4e0e\u00a0<span class=\"cnblogs_code\">_Function_base<\/span>\u00a0\uff0c\u4e24\u8005\u90fd\u662f\u5b9e\u73b0\u7ee7\u627f\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Function_base<\/span>\u00a0\u4e2d\u6709\u00a0<span class=\"cnblogs_code\">_Base_manager<\/span>\u00a0\u4e0e\u00a0<span class=\"cnblogs_code\">_Ref_manager<\/span>\u00a0\u4e24\u4e2a\u5d4c\u5957\u7c7b\u578b\uff0c\u5176\u4e2d\u540e\u8005\u8fd8\u7ee7\u627f\u4e86\u524d\u8005\uff0c\u5e76\u8986\u5199\u4e86\u51e0\u4e2a\u65b9\u6cd5\u3002\u4e24\u4e2a\u7c7b\u5b9a\u4e49\u4e86\u4e00\u7cfb\u5217\u9759\u6001\u65b9\u6cd5\uff0c\u7ee7\u627f\u53ea\u662f\u4e3a\u4e86\u907f\u514d\u4ee3\u7801\u91cd\u590d\u3002<\/p>\n<p><span class=\"cnblogs_code\">_Function_base<\/span>\u00a0\u542b\u6709\u4e24\u4e2a\u6570\u636e\u57df\uff0c\u4e00\u4e2a\u662f\u51fd\u6570\u6307\u9488\uff0c<span class=\"cnblogs_code\">_Function_base<\/span>\u00a0\u4e0e\u4e24\u4e2a\u5d4c\u5957\u7c7b\u578b\u4e4b\u95f4\u65e2\u662f\u5d4c\u5957\u53c8\u662f\u7ec4\u5408\uff1b\u53e6\u4e00\u4e2a\u662f\u00a0<span class=\"cnblogs_code\">_Any_data<\/span>\u00a0\u7c7b\u578b\u5bf9\u8c61\uff0c<span class=\"cnblogs_code\">_Function_base<\/span>\u00a0\u4e0e\u00a0<span class=\"cnblogs_code\">_Any_data<\/span>\u00a0\u4e4b\u95f4\u662f\u7ec4\u5408\u5173\u7cfb\u3002<\/p>\n<p>\u800c\u00a0<span class=\"cnblogs_code\">_Any_data<\/span>\u00a0\u662f\u4e00\u4e2a\u8054\u5408\u4f53\uff0c\u662f\u4e24\u90e8\u5206\u76f8\u540c\u5927\u5c0f\u6570\u636e\u7684\u8054\u5408\uff0c\u5206\u522b\u662f\u00a0<span class=\"cnblogs_code\">char<\/span>\u00a0\u6570\u7ec4\u548c\u00a0<span class=\"cnblogs_code\">_Nocopy_types<\/span>\u00a0\u7c7b\u578b\u5bf9\u8c61\uff0c\u540e\u8005\u53c8\u662f4\u79cd\u57fa\u672c\u7c7b\u578b\u7684\u8054\u5408\u3002<\/p>\n<p>\u5176\u4f59\u7684\u4e00\u4e9b\u7c7b\u4e0e\u51fd\u6570\uff0c\u90fd\u662f\u8d77\u8f85\u52a9\u4f5c\u7528\u7684\u3002\u81f3\u6b64\uff0c\u5bf9\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5b9a\u4e49\u7684\u5206\u6790\u5c31\u7ed3\u675f\u4e86\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_2_2\"><\/a>2.2 \u65b9\u6cd5\u7684\u529f\u80fd\u4e0e\u5b9e\u73b0<\/h3>\n<h4><a name=\"mark_2_2_1\"><\/a>2.2.1 \u591a\u6001\u6027\u7684\u4f53\u73b0<\/h4>\n<p>\u4e4b\u524d\u4e00\u76f4\u8bb2\uff0c<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u662f\u4e00\u4e2a\u591a\u6001\u7684\u51fd\u6570\u5bf9\u8c61\u5305\u88c5\u5668\uff0c\u5176\u4e2d\u7684\u96be\u70b9\u5c31\u5728\u4e8e\u591a\u6001\u3002\u4ec0\u4e48\u662f\u591a\u6001\uff1f\u4f60\u80fd\u770b\u5230\u8fd9\u91cc\uff0c\u6c34\u5e73\u80af\u5b9a\u4e0d\u4f4e\uff0c\u4e0d\u77e5\u9053\u591a\u6001\u662f\u4e0d\u53ef\u80fd\u7684\u3002Wikipedia\u5bf9<a title=\"Polymorphism (computer science)\" href=\"https:\/\/en.wikipedia.org\/wiki\/Polymorphism_(computer_science)\" target=\"_blank\" rel=\"noopener noreferrer\">polymorphism<\/a>\u7684\u5b9a\u4e49\u662f\uff1aIn programming languages and type theory, polymorphism is the provision of a single interface to entities of different types or the use of a single symbol to represent multiple different types.<\/p>\n<p>\u53ef\u4ee5\u8bf4\uff0c\u6211\u4eec\u8981\u5728\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u4e2d\u5904\u7406\u597d\u591a\u6001\uff0c\u5c31\u662f\u8981\u5904\u7406\u597d\u7c7b\u578b\u3002\u7c7b\u578b\u5f53\u7136\u4e0d\u80fd\u4e00\u4e2a\u4e2a\u679a\u4e3e\uff0c\u4f46\u53ef\u4ee5\u5206\u7c7b\u3002\u8fd9\u91cc\u53ef\u4ee5\u5206\u7c7b\u7684\u6709\u4e24\u5904\uff1a\u63a5\u53e3\u7c7b\u578b\uff0c\u5373\u7ec4\u6210\u6a21\u677f\u53c2\u6570\u7684\u7c7b\u578b\uff0c\u4ee5\u53ca\u5b9e\u73b0\u7c7b\u578b\uff0c\u5373\u7ed1\u5b9a\u7684\u4eff\u51fd\u6570\u7684\u7c7b\u578b\u3002\u4e0b\u9762\uff0c\u6211\u4eec\u5c31\u4ece\u8fd9\u4e24\u4e2a\u89d2\u5ea6\u5165\u624b\uff0c\u5206\u6790\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u662f\u5982\u4f55\u5b9e\u73b0\u7684\u3002<\/p>\n<h4><a name=\"mark_2_2_2\"><\/a>2.2.2 \u672c\u5730\u51fd\u6570\u5bf9\u8c61<\/h4>\n<p>\u5148\u6839\u636e\u4eff\u51fd\u6570\u7c7b\u578b\u5206\u7c7b\uff0c\u53ef\u4ee5\u5728\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5bf9\u8c61\u5185\u90e8\u5b58\u50a8\u7684\uff0c\u65e0\u9700heap\u7a7a\u95f4\u7684\uff0c\u5728\u8fd9\u4e00\u8282\u8ba8\u8bba\u3002\u76f8\u5173\u7684\u65b9\u6cd5\u6709\u4ee5\u4e0b3\u4e2a\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   static void\r\n 3   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n 4   _M_init_functor(_Any_data&amp; __functor, _Functor&amp;&amp; __f, true_type)\r\n 5   { new (__functor._M_access()) _Functor(std::move(__f)); }\r\n 6 \r\n 7 template&lt;typename _Functor&gt;\r\n 8   static void\r\n 9   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n10   _M_clone(_Any_data&amp; __dest, const _Any_data&amp; __source, true_type)\r\n11   {\r\n12     new (__dest._M_access()) _Functor(__source._M_access&lt;_Functor&gt;());\r\n13   }\r\n14 \r\n15 template&lt;typename _Functor&gt;\r\n16   static void\r\n17   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n18   _M_destroy(_Any_data&amp; __victim, true_type)\r\n19   {\r\n20     __victim._M_access&lt;_Functor&gt;().~_Functor();\r\n21   }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">_M_init_functor<\/span>\u00a0\u7528\u4e8e\u521d\u59cb\u5316\u5bf9\u8c61\uff0c\u5728\u7a7a\u767d\u533a\u57df\u4e0a\u7528placement\u00a0<span class=\"cnblogs_code\">new<\/span>\u00a0\u79fb\u52a8\u6784\u9020\u4e86\u51fd\u6570\u5bf9\u8c61\u3002<\/p>\n<p><span class=\"cnblogs_code\">_M_clone<\/span>\u00a0\u7528\u4e8e\u590d\u5236\u5bf9\u8c61\uff0c\u5728\u76ee\u6807\u7684\u7a7a\u767d\u533a\u57df\u4e0a\u7528placement\u00a0<span class=\"cnblogs_code\">new<\/span>\u00a0\u62f7\u8d1d\u6784\u9020\u548c\u51fd\u6570\u5bf9\u8c61\u3002<\/p>\n<p><span class=\"cnblogs_code\">_M_destroy<\/span>\u00a0\u7528\u4e8e\u9500\u6bc1\u5bf9\u8c61\uff0c\u5bf9\u51fd\u6570\u5bf9\u8c61\u663e\u5f0f\u8c03\u7528\u4e86\u6790\u6784\u51fd\u6570\u3002<\/p>\n<h4><a name=\"mark_2_2_3\"><\/a>2.2.3 heap\u51fd\u6570\u5bf9\u8c61<\/h4>\n<p>\u7136\u540e\u6765\u770b\u51fd\u6570\u5bf9\u8c61\u5b58\u50a8\u5728heap\u4e0a\u7684\u60c5\u51b5\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   static void\r\n 3   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n 4   _M_init_functor(_Any_data&amp; __functor, _Functor&amp;&amp; __f, false_type)\r\n 5   { __functor._M_access&lt;_Functor*&gt;() = new _Functor(std::move(__f)); }\r\n 6 \r\n 7 template&lt;typename _Functor&gt;\r\n 8   static void\r\n 9   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n10   _M_clone(_Any_data&amp; __dest, const _Any_data&amp; __source, false_type)\r\n11   {\r\n12     __dest._M_access&lt;_Functor*&gt;() =\r\n13       new _Functor(*__source._M_access&lt;_Functor*&gt;());\r\n14   }\r\n15 \r\n16 template&lt;typename _Functor&gt;\r\n17   static void\r\n18   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n19   _M_destroy(_Any_data&amp; __victim, false_type)\r\n20   {\r\n21     delete __victim._M_access&lt;_Functor*&gt;();\r\n22   }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">_M_access&lt;_Functor*&gt;()<\/span>\u00a0\u5c06\u7a7a\u767d\u533a\u57df\u89e3\u91ca\u4e3a\u4eff\u51fd\u6570\u7684\u6307\u9488\uff0c\u5e76\u8fd4\u56de\u5176\u5f15\u7528\uff0c\u5b9e\u73b0\u4e86\u8fd9\u7247\u533a\u57df\u7684\u5206\u65f6\u590d\u7528\u3002\u524d\u4e24\u4e2a\u65b9\u6cd5\u90fd\u6bd4\u524d\u4e00\u79cd\u60c5\u51b5\u591a\u4e00\u5c42\u95f4\u63a5\uff0c\u800c\u9500\u6bc1\u65b9\u6cd5\u5219\u76f4\u63a5\u8c03\u7528\u4e86\u00a0<span class=\"cnblogs_code\">delete<\/span>\u00a0\u3002<\/p>\n<h4><a name=\"mark_2_2_4\"><\/a>2.2.4 \u4e24\u79cd\u5b58\u50a8\u7ed3\u6784\u5982\u4f55\u7edf\u4e00<\/h4>\n<p>\u5c3d\u7ba1\u6211\u4eec\u4e0d\u5f97\u4e0d\u5206\u7c7b\u8ba8\u8bba\uff0c\u4f46\u4e3a\u4e86\u65b9\u4fbf\u4f7f\u7528\uff0c\u8fd8\u9700\u8981\u4e00\u4e2a\u7edf\u4e00\u7684\u63a5\u53e3\u3002\u4e0d\u77e5\u4f60\u6709\u6ca1\u6709\u6ce8\u610f\u5230\uff0c\u4e0a\u9762\u6bcf\u4e00\u4e2a\u65b9\u6cd5\u90fd\u6709\u4e00\u4e2a\u672a\u547d\u540d\u7684\u53c2\u6570\u653e\u5728\u6700\u540e\uff0c\u5728\u65b9\u6cd5\u4e2d\u4e5f\u6ca1\u6709\u7528\u5230\u3002\u524d\u4e00\u79cd\u60c5\u51b5\uff0c\u8fd9\u4e2a\u53c2\u6570\u90fd\u662f\u00a0<span class=\"cnblogs_code\">true_type<\/span>\u00a0\u7c7b\u578b\uff0c\u800c\u540e\u4e00\u79cd\u90fd\u662f\u00a0<span class=\"cnblogs_code\">false_type<\/span>\u00a0\u7c7b\u578b\u3002\u8fd9\u4e2a\u6280\u5de7\u79f0\u4e3atag dispatching\uff0c\u5728\u8c03\u7528\u65f6\u6839\u636e\u7c7b\u578b\u7279\u5f81\u786e\u5b9a\u8fd9\u4e2a\u4f4d\u7f6e\u7684\u53c2\u6570\u7c7b\u578b\uff0c\u4ece\u800c\u901a\u8fc7\u91cd\u8f7d\u51b3\u5b9a\u8c03\u7528\u54ea\u4e00\u4e2a\u3002<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   static void\r\n 3   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n 4   _M_init_functor(_Any_data&amp; __functor, _Functor&amp;&amp; __f)\r\n 5   { _M_init_functor(__functor, std::move(__f), _Local_storage()); }\r\n 6 \r\n 7 template&lt;typename _Functor&gt;\r\n 8   static bool\r\n 9   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n10   _M_manager(_Any_data&amp; __dest, const _Any_data&amp; __source,\r\n11              _Manager_operation __op)\r\n12   {\r\n13     switch (__op)\r\n14       {\r\n15   #ifdef __GXX_RTTI\r\n16       case __get_type_info:\r\n17         __dest._M_access&lt;const type_info*&gt;() = &amp;typeid(_Functor);\r\n18         break;\r\n19   #endif\r\n20       case __get_functor_ptr:\r\n21         __dest._M_access&lt;_Functor*&gt;() = _M_get_pointer(__source);\r\n22         break;\r\n23 \r\n24       case __clone_functor:\r\n25         _M_clone(__dest, __source, _Local_storage());\r\n26         break;\r\n27 \r\n28       case __destroy_functor:\r\n29         _M_destroy(__dest, _Local_storage());\r\n30         break;\r\n31       }\r\n32     return false;\r\n33   }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u8fd9\u4e2a\u7248\u672c\u7684\u00a0<span class=\"cnblogs_code\">_M_init_functor()<\/span>\u00a0\u53ea\u6709\u4e24\u4e2a\u53c2\u6570\uff0c\u52a0\u4e0a\u7b2c\u4e09\u4e2a\u53c2\u6570\u59d4\u6258\u7ed9\u91cd\u8f7d\u7248\u672c\u5904\u7406\uff0c\u8fd9\u7b2c\u4e09\u4e2a\u53c2\u6570\u662f\u4e00\u4e2a\u00a0<span class=\"cnblogs_code\">_Local_storage<\/span>\u00a0\u7c7b\u7684\u5bf9\u8c61\uff0c\u5b83\u6839\u636e\u00a0<span class=\"cnblogs_code\">__stored_locally<\/span>\u00a0\u800c\u6210\u4e3a\u00a0<span class=\"cnblogs_code\">true_type<\/span>\u00a0\u4e0e\u00a0<span class=\"cnblogs_code\">false_type<\/span>\u00a0\uff0c\u4ece\u800c\u533a\u5206\u5f00\u4e24\u4e2a\u91cd\u8f7d\u3002<\/p>\n<p><span class=\"cnblogs_code\">_M_manager()<\/span>\u00a0\u65b9\u6cd5\uff0c\u540c\u6837\u5730\uff0c\u5229\u7528tag dispatching\u628a\u53e6\u4e24\u7ec4\u65b9\u6cd5\u7edf\u4e00\u8d77\u6765\u3002\u5b83\u901a\u8fc7\u7b2c\u4e09\u4e2a\u679a\u4e3e\u7c7b\u578b\u53c2\u6570\u6765\u786e\u5b9a\u9700\u8981\u7684\u64cd\u4f5c\u3002<\/p>\n<p>\u4f46\u662f\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u7684\u8fd4\u56de\u503c\u662f\u00a0<span class=\"cnblogs_code\">bool<\/span>\u00a0\uff0c\u600e\u4e48\u4f20\u51fa\u00a0<span class=\"cnblogs_code\">type_info<\/span>\u00a0\u4e0e\u51fd\u6570\u5bf9\u8c61\u6307\u9488\u5462\uff1f\u5b83\u4eec\u5c06\u8fd4\u56de\u503c\u5199\u5165\u7b2c\u4e00\u4e2a\u53c2\u6570\u6240\u6307\u5411\u7684\u7a7a\u95f4\u4e2d\u3002\u8bf4\u8d77\u5229\u7528\u53c2\u6570\u6765\u4f20\u9012\u8fd4\u56de\u503c\uff0c\u6211\u5c31\u60f3\u8d77C\u4e2d\u7684\u6307\u9488\u3001C++\u4e2d\u7684\u5f15\u7528\u3001RVO\u3001Java\u4e2d\u7684\u5305\u88f9\u7c7b\u578b\u3001C#\u4e2d\u7684\u00a0<span class=\"cnblogs_code\">out<\/span>\u00a0\u5173\u952e\u5b57\u2026\u2026\u8fd9\u91cc\u7684\u5904\u7406\u65b9\u6cd5\u4e0d\u4ec5\u89e3\u51b3\u4e86\u8fd4\u56de\u503c\u7684\u95ee\u9898\uff0c\u540c\u65f6\u4e5f\u4f7f\u5404\u4e2a\u64cd\u4f5c\u7684\u53c2\u6570\u7edf\u4e00\u8d77\u6765\u3002<\/p>\n<p>\u4e00\u4e2a\u503c\u5f97\u601d\u8003\u7684\u95ee\u9898\u662f\u4e3a\u4ec0\u4e48\u4e0d\u628a\u00a0<span class=\"cnblogs_code\">_M_init_functor()<\/span>\u00a0\u4e5f\u653e\u5230\u00a0<span class=\"cnblogs_code\">_M_manager()<\/span>\u00a0\u4e2d\u53bb\uff1f\u7b54\u6848\u662f\uff0c\u8c03\u7528\u00a0<span class=\"cnblogs_code\">_M_init_functor()<\/span>\u00a0\u7684\u5730\u65b9\u5728\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u6a21\u677f\u6784\u9020\u6216\u6a21\u677f\u8d4b\u503c\u51fd\u6570\u4e2d\uff0c\u6b64\u65f6\u662f\u77e5\u9053\u4eff\u51fd\u6570\u7c7b\u578b\u7684\uff1b\u800c\u5176\u4ed6\u64cd\u4f5c\u88ab\u8c03\u7528\u65f6\uff0c\u4e3b\u8c03\u51fd\u6570\u662f\u4e0d\u77e5\u9053\u4eff\u51fd\u6570\u7c7b\u578b\u7684\uff0c\u5c31\u5fc5\u987b\u7528\u51fd\u6570\u6307\u9488\u5b58\u50a8\u8d77\u6765\uff1b\u4e3a\u4e86\u8282\u7701\u7a7a\u95f4\uff0c\u5c31\u5f15\u5165\u4e00\u4e2a\u679a\u4e3e\u7c7b\u00a0<span class=\"cnblogs_code\">_Manager_operation<\/span>\u00a0\uff0c\u628a\u51e0\u79cd\u64cd\u4f5c\u5408\u5e76\u5230\u4e00\u4e2a\u51fd\u6570\u4e2d\u3002<\/p>\n<p>\u5b9e\u9645\u4e0a\u8fd9\u4e00\u5c42\u53ef\u4ee5\u5148\u4e0d\u7edf\u4e00\uff0c\u5c31\u662f\u5199\u4e24\u79cd\u60c5\u51b5\u7684\u00a0<span class=\"cnblogs_code\">_M_manager<\/span>\u00a0\uff0c\u7136\u540e\u5230\u4e0a\u4e00\u5c42\u518d\u7edf\u4e00\uff0c\u4f46\u662f\u4f1a\u589e\u52a0\u4ee3\u7801\u91cf\u3002<\/p>\n<p>\u9664\u6b64\u4ee5\u5916\uff0c\u8fd8\u6709\u4e00\u79cd\u7b80\u5355\u7684\u65b9\u6cd5\u5c06\u4e24\u8005\u7edf\u4e00\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   static _Functor*\r\n 3   _Function_base::_Base_manager&lt;_Functor&gt;::\r\n 4   _M_get_pointer(const _Any_data&amp; __source)\r\n 5   {\r\n 6     const _Functor* __ptr =\r\n 7       __stored_locally? std::__addressof(__source._M_access&lt;_Functor&gt;())\r\n 8                       : __source._M_access&lt;_Functor*&gt;();\r\n 9     return const_cast&lt;_Functor*&gt;(__ptr);\r\n10   }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u4e09\u76ee\u8fd0\u7b97\u7b26\u7684\u6761\u4ef6\u662f\u4e00\u4e2a\u9759\u6001\u5e38\u91cf\uff0c\u7f16\u8bd1\u5668\u4f1a\u4f18\u5316\uff0c\u4e0d\u6d6a\u8d39\u7a0b\u5e8f\u7a7a\u95f4\uff0c\u4e5f\u4e0d\u9700\u8981\u5728\u8fd0\u884c\u65f6\u5224\u65ad\uff0c\u6548\u679c\u4e0e\u524d\u4e00\u79cd\u65b9\u6cd5\u76f8\u540c\u3002\u81f3\u4e8e\u53e6\u5916\u4e24\u4e2a\u65b9\u6cd5\uff08\u6307\u51fd\u6570\uff09\u4e3a\u4ec0\u4e48\u4e0d\u7528\u8fd9\u79cd\u65b9\u6cd5\uff08\u6307\u5c06\u4e24\u79cd\u60c5\u51b5\u7edf\u4e00\u7684\u65b9\u6cd5\uff09\uff0c\u53ef\u80fd\u662f\u4e3a\u4e86\u53ef\u8bfb\u6027\u5427\u3002<\/p>\n<h4><a name=\"mark_2_2_5\"><\/a>2.2.5 \u6839\u636e\u5f62\u5f0f\u533a\u5206\u4eff\u51fd\u6570\u7c7b\u578b<\/h4>\n<p>\u5728\u4e0b\u9762\u4e00\u5c42\u89e3\u51b3\u4e86\u4e0d\u540c\u5b58\u50a8\u7ed3\u6784\u7684\u95ee\u9898\u540e\uff0c\u6211\u4eec\u8fd8\u8981\u8003\u8651\u51e0\u79cd\u7279\u6b8a\u60c5\u51b5\u3002<\/p>\n<p><span class=\"cnblogs_code\">_M_not_empty_function()<\/span>\u00a0\u7528\u4e8e\u5224\u65ad\u53c2\u6570\u662f\u5426\u975e\u7a7a\uff0c\u800c\u4e0d\u540c\u7c7b\u578b\u7684\u5224\u5b9a\u65b9\u6cd5\u662f\u4e0d\u540c\u7684\u3002\u8fd9\u91cc\u7684\u89e3\u51b3\u65b9\u6848\u5f88\u7b80\u5355\uff0c\u6a21\u677f\u65b9\u6cd5\u91cd\u8f7d\u5373\u53ef\u3002<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   template&lt;typename _Signature&gt;\r\n 3     static bool\r\n 4     _Function_base::_Base_manager&lt;_Functor&gt;::\r\n 5     _M_not_empty_function(const function&lt;_Signature&gt;&amp; __f)\r\n 6     { return static_cast&lt;bool&gt;(__f); }\r\n 7 \r\n 8 template&lt;typename _Functor&gt;\r\n 9   template&lt;typename _Tp&gt;\r\n10     static bool\r\n11     _Function_base::_Base_manager&lt;_Functor&gt;::\r\n12     _M_not_empty_function(const _Tp*&amp; __fp)\r\n13     { return __fp; }\r\n14 \r\n15 template&lt;typename _Functor&gt;\r\n16   template&lt;typename _Class, typename _Tp&gt;\r\n17     static bool\r\n18     _Function_base::_Base_manager&lt;_Functor&gt;::\r\n19     _M_not_empty_function(_Tp _Class::* const&amp; __mp)\r\n20     { return __mp; }\r\n21 \r\n22 template&lt;typename _Functor&gt;\r\n23   template&lt;typename _Tp&gt;\r\n24     static bool\r\n25     _Function_base::_Base_manager&lt;_Functor&gt;::\r\n26     _M_not_empty_function(const _Tp&amp;)\r\n27     { return true; }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u5728\u8c03\u7528\u65f6\uff0c\u666e\u901a\u51fd\u6570\u5bf9\u8c61\u3001<span class=\"cnblogs_code\">std::reference_wrapper<\/span>\u00a0\u5bf9\u8c61\u4e0e\u6210\u5458\u6307\u9488\u7684\u8c03\u7528\u65b9\u6cd5\u662f\u4e0d\u540c\u7684\uff0c\u4e5f\u9700\u8981\u5206\u7c7b\u8ba8\u8bba\u3002<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre>1 template&lt;typename _Res, typename _Functor, typename... _ArgTypes&gt;\r\n2   static _Res\r\n3   _Function_handler&lt;_Res(_ArgTypes...), _Functor&gt;::\r\n4   _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args)\r\n5   {\r\n6     return (*_Base::_M_get_pointer(__functor))(\r\n7         std::forward&lt;_ArgTypes&gt;(__args)...);\r\n8   }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u5bf9\u4e8e\u666e\u901a\u51fd\u6570\u5bf9\u8c61\uff0c\u51fd\u6570\u8c03\u7528\u6ca1\u4ec0\u4e48\u7279\u6b8a\u7684\u3002\u6ce8\u610f\u81ea\u5b9a\u4e49\u00a0<span class=\"cnblogs_code\">operator()<\/span>\u00a0\u5fc5\u987b\u662f\u00a0<span class=\"cnblogs_code\">const<\/span>\u00a0\u7684\u3002<\/p>\n<p>\u5bf9\u4e8e\u00a0<span class=\"cnblogs_code\">std::reference_wrapper<\/span>\u00a0\u5bf9\u8c61\uff0c\u7531\u4e8e\u5305\u88c5\u7684\u5bf9\u8c61\u5b58\u50a8\u4e3a\u6307\u9488\uff0c\u56e0\u6b64\u5b58\u50a8\u7ed3\u6784\u4e0e\u666e\u901a\u51fd\u6570\u5bf9\u8c61\u6709\u6240\u4e0d\u540c\uff0c\u76f8\u5e94\u5730\u8c03\u7528\u4e5f\u4e0d\u540c\u3002<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor&gt;\r\n 2   static void\r\n 3   _Function_base::_Ref_manager&lt;_Functor&gt;::\r\n 4   _M_init_functor(_Any_data&amp; __functor, reference_wrapper&lt;_Functor&gt; __f)\r\n 5   {\r\n 6     _Base::_M_init_functor(__functor, std::__addressof(__f.get()));\r\n 7   }\r\n 8 \r\n 9 template&lt;typename _Functor&gt;\r\n10   static bool\r\n11   _Function_base::_Ref_manager&lt;_Functor&gt;::\r\n12   _M_manager(_Any_data&amp; __dest, const _Any_data&amp; __source,\r\n13              _Manager_operation __op)\r\n14   {\r\n15     switch (__op)\r\n16       {\r\n17   #ifdef __GXX_RTTI\r\n18       case __get_type_info:\r\n19         __dest._M_access&lt;const type_info*&gt;() = &amp;typeid(_Functor);\r\n20         break;\r\n21   #endif\r\n22       case __get_functor_ptr:\r\n23         __dest._M_access&lt;_Functor*&gt;() = *_Base::_M_get_pointer(__source);\r\n24         return is_const&lt;_Functor&gt;::value;\r\n25         break;\r\n26 \r\n27       default:\r\n28         _Base::_M_manager(__dest, __source, __op);\r\n29       }\r\n30     return false;\r\n31   }\r\n32 \r\n33 template&lt;typename _Res, typename _Functor, typename... _ArgTypes&gt;\r\n34   static _Res\r\n35   _Function_handler&lt;_Res(_ArgTypes...), reference_wrapper&lt;_Functor&gt; &gt;::\r\n36   _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args)\r\n37   {\r\n38     return __callable_functor(**_Base::_M_get_pointer(__functor))(\r\n39         std::forward&lt;_ArgTypes&gt;(__args)...);\r\n40   }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u78b0\u5230\u4e24\u4e2a\u661f\u53f7\u662f\u4e0d\u662f\u6709\u70b9\u6655\uff1f\u5176\u5b9e\u53ea\u8981\u60f3\uff0c\u4e00\u822c\u60c5\u51b5\u4e0b\u5b58\u50a8\u51fd\u6570\u5bf9\u8c61\u7684\u5730\u65b9\u73b0\u5728\u5b58\u50a8\u6307\u9488\uff0c\u6240\u4ee5\u8981\u83b7\u5f97\u539f\u59cb\u5bf9\u8c61\uff0c\u53ea\u9700\u8981\u6bd4\u4e00\u822c\u60c5\u51b5\u591a\u4e00\u6b21\u89e3\u5f15\u7528\uff0c\u8fd9\u6837\u5c31\u5bb9\u6613\u7406\u89e3\u4e86\u3002<\/p>\n<p>\u5bf9\u4e8e\u6210\u5458\u6307\u9488\uff0c\u60c5\u51b5\u53c8\u6709\u4e00\u70b9\u4e0d\u4e00\u6837\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Class, typename _Member, typename... _ArgTypes&gt;\r\n 2   static bool\r\n 3   _Function_handler&lt;void(_ArgTypes...), _Member _Class::*&gt;::\r\n 4   _M_manager(_Any_data&amp; __dest, const _Any_data&amp; __source,\r\n 5              _Manager_operation __op)\r\n 6   {\r\n 7     switch (__op)\r\n 8       {\r\n 9 #ifdef __GXX_RTTI\r\n10       case __get_type_info:\r\n11         __dest._M_access&lt;const type_info*&gt;() = &amp;typeid(_Functor);\r\n12         break;\r\n13 #endif\r\n14       case __get_functor_ptr:\r\n15         __dest._M_access&lt;_Functor*&gt;() =\r\n16           &amp;_Base::_M_get_pointer(__source)-&gt;__value;\r\n17         break;\r\n18 \r\n19       default:\r\n20         _Base::_M_manager(__dest, __source, __op);\r\n21       }\r\n22     return false;\r\n23   }\r\n24 \r\n25 template&lt;typename _Class, typename _Member, typename _Res,\r\n26          typename... _ArgTypes&gt;\r\n27   static _Res\r\n28   _Function_handler&lt;_Res(_ArgTypes...), _Member _Class::*&gt;::\r\n29   _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args)\r\n30   {\r\n31     return std::mem_fn(_Base::_M_get_pointer(__functor)-&gt;__value)(\r\n32         std::forward&lt;_ArgTypes&gt;(__args)...);\r\n33   }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u6211\u4e00\u76f4\u8bf4\u201c\u6210\u5458\u6307\u9488\u201d\uff0c\u800c\u4e0d\u662f\u201c\u6210\u5458\u51fd\u6570\u6307\u9488\u201d\uff0c\u662f\u56e0\u4e3a\u6570\u636e\u6210\u5458\u6307\u9488\u4e5f\u662f\u53ef\u4ee5\u7ed1\u5b9a\u7684\uff0c\u8fd9\u79cd\u60c5\u51b5\u5728\u00a0<span class=\"cnblogs_code\">std::mem_fn()<\/span>\u00a0\u4e2d\u5df2\u7ecf\u5904\u7406\u597d\u4e86\u3002<\/p>\n<p><span class=\"cnblogs_code\">void<\/span>\u00a0\u8fd4\u56de\u7c7b\u578b\u7684\u504f\u7279\u5316\u672c\u5e94\u63a5\u4e0b\u6765\u8ba8\u8bba\uff0c\u4f46\u4e4b\u524d\u8bb2\u8fc7\uff0c\u8fd9\u4e2a\u51fd\u6570\u88ab\u901a\u8fc7\u7ee7\u627f\u590d\u7528\u4e86\u3002\u5b9e\u9645\u4e0a\uff0c\u5982\u679c\u628a\u8fd9\u91cc\u7684\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u6539\u4e3a\u6a21\u677f\u7c7b\u578b\uff0c\u7136\u540e\u4ea4\u6362\u4e24\u4e2a\u00a0<span class=\"cnblogs_code\">_Function_handler<\/span>\u00a0\u504f\u7279\u5316\u7684\u7ee7\u627f\u5173\u7cfb\uff0c\u6548\u679c\u8fd8\u662f\u4e00\u6837\u7684\uff0c\u6240\u4ee5\u5c31\u5728\u8fd9\u91cc\u5148\u8ba8\u8bba\u4e86\u3002<\/p>\n<p>\u6700\u540e\u4e00\u4e2a\u9700\u8981\u533a\u5206\u7684\u7c7b\u578b\uff0c\u662f\u8fd4\u56de\u503c\u7c7b\u578b\uff0c\u5c5e\u4e8e\u63a5\u53e3\u7c7b\u578b\u3002\u4e4b\u524d\u90fd\u662f\u975e\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u7248\u672c\uff0c\u4e0b\u9762\u8fd8\u6709\u51e0\u4e2a\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u7684\u504f\u7279\u5316\uff1a<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre> 1 template&lt;typename _Functor, typename... _ArgTypes&gt;\r\n 2   static void\r\n 3   _Function_handler&lt;void(_ArgTypes...), _Functor&gt;::\r\n 4   _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args)\r\n 5   {\r\n 6     (*_Base::_M_get_pointer(__functor))(\r\n 7         std::forward&lt;_ArgTypes&gt;(__args)...);\r\n 8   }\r\n 9 \r\n10 template&lt;typename _Functor, typename... _ArgTypes&gt;\r\n11   static void\r\n12   _Function_handler&lt;void(_ArgTypes...), reference_wrapper&lt;_Functor&gt; &gt;::\r\n13   _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args)\r\n14   {\r\n15     __callable_functor(**_Base::_M_get_pointer(__functor))(\r\n16         std::forward&lt;_ArgTypes&gt;(__args)...);\r\n17   }\r\n18 \r\n19 template&lt;typename _Class, typename _Member, typename... _ArgTypes&gt;\r\n20   static void\r\n21   _Function_handler&lt;void(_ArgTypes...), _Member _Class::*&gt;::\r\n22   _M_invoke(const _Any_data&amp; __functor, _ArgTypes... __args)\r\n23   {\r\n24     std::mem_fn(_Base::_M_get_pointer(__functor)-&gt;__value)(\r\n25         std::forward&lt;_ArgTypes&gt;(__args)...);\r\n26   }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p><span class=\"cnblogs_code\">void<\/span>\u00a0\u53ea\u662f\u5220\u9664\u4e86\u00a0<span class=\"cnblogs_code\">return<\/span>\u00a0\u5173\u952e\u5b57\u7684\u975e\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u7248\u672c\uff0c\u56e0\u6b64\u00a0<span class=\"cnblogs_code\">void<\/span>\u00a0\u8fd4\u56de\u7c7b\u578b\u7684\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5bf9\u8c61\u53ef\u4ee5\u7ed1\u5b9a\u4efb\u4f55\u8fd4\u56de\u503c\u7684\u51fd\u6570\u5bf9\u8c61\u3002<\/p>\n<h4><a name=\"mark_2_2_6\"><\/a>2.2.6 \u5b9e\u73b0\u7ec4\u88c5\u6210\u63a5\u53e3<\/h4>\n<p>\u6211\u4eec\u7ec8\u4e8e\u8ba8\u8bba\u5b8c\u4e86\u5404\u79cd\u60c5\u51b5\uff0c\u63a5\u4e0b\u6765\u8ba9\u6211\u4eec\u6765\u89c1\u8bc1\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u7684\u5927\u548c\u8c10\uff1a\u5982\u4f55\u7528\u8fd9\u4e9b\u65b9\u6cd5\u7ec4\u88c5\u6210\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u3002<\/p>\n<div class=\"cnblogs_code\">\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<pre>  1 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n  2   function&lt;_Res(_ArgTypes...)&gt;::\r\n  3   function() noexcept\r\n  4   : _Function_base() { }\r\n  5 \r\n  6 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n  7   function&lt;_Res(_ArgTypes...)&gt;::\r\n  8   function(nullptr_t) noexcept\r\n  9   : _Function_base() { }\r\n 10 \r\n 11 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 12   function&lt;_Res(_ArgTypes...)&gt;::\r\n 13   function(function&amp;&amp; __x) : _Function_base()\r\n 14   {\r\n 15     __x.swap(*this);\r\n 16   }\r\n 17 \r\n 18 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 19   auto\r\n 20   function&lt;_Res(_ArgTypes...)&gt;::\r\n 21   operator=(const function&amp; __x)\r\n 22   -&gt; function&amp;\r\n 23   {\r\n 24     function(__x).swap(*this);\r\n 25     return *this;\r\n 26   }\r\n 27 \r\n 28 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 29   auto\r\n 30   function&lt;_Res(_ArgTypes...)&gt;::\r\n 31   operator=(function&amp;&amp; __x)\r\n 32   -&gt; function&amp;\r\n 33   {\r\n 34     function(std::move(__x)).swap(*this);\r\n 35     return *this;\r\n 36   }\r\n 37 \r\n 38 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 39   auto\r\n 40   function&lt;_Res(_ArgTypes...)&gt;::\r\n 41   operator=(nullptr_t)\r\n 42   -&gt; function&amp;\r\n 43   {\r\n 44     if (_M_manager)\r\n 45       {\r\n 46         _M_manager(_M_functor, _M_functor, __destroy_functor);\r\n 47         _M_manager = 0;\r\n 48         _M_invoker = 0;\r\n 49       }\r\n 50     return *this;\r\n 51   }\r\n 52 \r\n 53 template&lt;typename _Functor&gt;\r\n 54   auto\r\n 55   function&lt;_Res(_ArgTypes...)&gt;::\r\n 56   operator=(_Functor&amp;&amp; __f)\r\n 57   -&gt; _Requires&lt;_Callable&lt;_Functor&gt;, function&amp;&gt;\r\n 58   {\r\n 59     function(std::forward&lt;_Functor&gt;(__f)).swap(*this);\r\n 60     return *this;\r\n 61   }\r\n 62 \r\n 63 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 64   template&lt;typename _Functor&gt;\r\n 65     auto\r\n 66     function&lt;_Res(_ArgTypes...)&gt;::\r\n 67     -&gt; function&amp;\r\n 68     operator=(reference_wrapper&lt;_Functor&gt; __f) noexcept\r\n 69     {\r\n 70       function(__f).swap(*this);\r\n 71       return *this;\r\n 72     }\r\n 73 \r\n 74 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 75   void\r\n 76   function&lt;_Res(_ArgTypes...)&gt;::\r\n 77   swap(function&amp; __x)\r\n 78   {\r\n 79     std::swap(_M_functor, __x._M_functor);\r\n 80     std::swap(_M_manager, __x._M_manager);\r\n 81     std::swap(_M_invoker, __x._M_invoker);\r\n 82   }\r\n 83 \r\n 84 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 85   function&lt;_Res(_ArgTypes...)&gt;::\r\n 86   operator bool() const noexcept\r\n 87   { return !_M_empty(); }\r\n 88 \r\n 89 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n 90   function&lt;_Res(_ArgTypes...)&gt;::\r\n 91   function(const function&amp; __x)\r\n 92   : _Function_base()\r\n 93   {\r\n 94     if (static_cast&lt;bool&gt;(__x))\r\n 95       {\r\n 96         _M_invoker = __x._M_invoker;\r\n 97         _M_manager = __x._M_manager;\r\n 98         __x._M_manager(_M_functor, __x._M_functor, __clone_functor);\r\n 99       }\r\n100   }\r\n101 \r\n102 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n103   template&lt;typename _Functor, typename&gt;\r\n104     function&lt;_Res(_ArgTypes...)&gt;::\r\n105     function(_Functor __f)\r\n106     : _Function_base()\r\n107     {\r\n108       typedef _Function_handler&lt;_Signature_type, _Functor&gt; _My_handler;\r\n109 \r\n110       if (_My_handler::_M_not_empty_function(__f))\r\n111         {\r\n112           _My_handler::_M_init_functor(_M_functor, std::move(__f));\r\n113           _M_invoker = &amp;_My_handler::_M_invoke;\r\n114           _M_manager = &amp;_My_handler::_M_manager;\r\n115         }\r\n116     }\r\n117 \r\n118 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n119   _Res\r\n120   function&lt;_Res(_ArgTypes...)&gt;::\r\n121   operator()(_ArgTypes... __args) const\r\n122   {\r\n123     if (_M_empty())\r\n124       __throw_bad_function_call();\r\n125     return _M_invoker(_M_functor, std::forward&lt;_ArgTypes&gt;(__args)...);\r\n126   }\r\n127 \r\n128 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n129   const type_info&amp;\r\n130   function&lt;_Res(_ArgTypes...)&gt;::\r\n131   target_type() const noexcept\r\n132   {\r\n133     if (_M_manager)\r\n134       {\r\n135         _Any_data __typeinfo_result;\r\n136         _M_manager(__typeinfo_result, _M_functor, __get_type_info);\r\n137         return *__typeinfo_result._M_access&lt;const type_info*&gt;();\r\n138       }\r\n139     else\r\n140       return typeid(void);\r\n141   }\r\n142 \r\n143 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n144   template&lt;typename _Functor&gt;\r\n145     _Functor*\r\n146     function&lt;_Res(_ArgTypes...)&gt;::\r\n147     target() noexcept\r\n148     {\r\n149       if (typeid(_Functor) == target_type() &amp;&amp; _M_manager)\r\n150         {\r\n151           _Any_data __ptr;\r\n152           if (_M_manager(__ptr, _M_functor, __get_functor_ptr)\r\n153               &amp;&amp; !is_const&lt;_Functor&gt;::value)\r\n154             return 0;\r\n155           else\r\n156             return __ptr._M_access&lt;_Functor*&gt;();\r\n157         }\r\n158       else\r\n159         return 0;\r\n160     }\r\n161 \r\n162 template&lt;typename _Res, typename... _ArgTypes&gt;\r\n163   template&lt;typename _Functor&gt;\r\n164     const _Functor*\r\n165     function&lt;_Res(_ArgTypes...)&gt;::\r\n166     target() const noexcept\r\n167     {\r\n168       if (typeid(_Functor) == target_type() &amp;&amp; _M_manager)\r\n169         {\r\n170           _Any_data __ptr;\r\n171           _M_manager(__ptr, _M_functor, __get_functor_ptr);\r\n172           return __ptr._M_access&lt;const _Functor*&gt;();\r\n173         }\r\n174       else\r\n175         return 0;\r\n176     }\r\n177 \r\n178 template&lt;typename _Res, typename... _Args&gt;\r\n179   inline bool\r\n180   operator==(const function&lt;_Res(_Args...)&gt;&amp; __f, nullptr_t) noexcept\r\n181   { return !static_cast&lt;bool&gt;(__f); }\r\n182 \r\n183 template&lt;typename _Res, typename... _Args&gt;\r\n184   inline bool\r\n185   operator==(nullptr_t, const function&lt;_Res(_Args...)&gt;&amp; __f) noexcept\r\n186   { return !static_cast&lt;bool&gt;(__f); }\r\n187 \r\n188 template&lt;typename _Res, typename... _Args&gt;\r\n189   inline bool\r\n190   operator!=(const function&lt;_Res(_Args...)&gt;&amp; __f, nullptr_t) noexcept\r\n191   { return static_cast&lt;bool&gt;(__f); }\r\n192 \r\n193 template&lt;typename _Res, typename... _Args&gt;\r\n194   inline bool\r\n195   operator!=(nullptr_t, const function&lt;_Res(_Args...)&gt;&amp; __f) noexcept\r\n196   { return static_cast&lt;bool&gt;(__f); }\r\n197 \r\n198 template&lt;typename _Res, typename... _Args&gt;\r\n199   inline void\r\n200   swap(function&lt;_Res(_Args...)&gt;&amp; __x, function&lt;_Res(_Args...)&gt;&amp; __y)\r\n201   { __x.swap(__y); }<\/pre>\n<div class=\"cnblogs_code_toolbar\"><span class=\"cnblogs_code_copy\"><a title=\"\u590d\u5236\u4ee3\u7801\"><img decoding=\"async\" src=\"https:\/\/common.cnblogs.com\/images\/copycode.gif\" alt=\"\u590d\u5236\u4ee3\u7801\" \/><\/a><\/span><\/div>\n<\/div>\n<p>\u6211\u4eec\u4ece\u00a0<span class=\"cnblogs_code\">swap()<\/span>\u00a0\u5f00\u59cb\u5165\u624b\u3002<span class=\"cnblogs_code\">swap()<\/span>\u00a0\u65b9\u6cd5\u53ea\u662f\u7b80\u5355\u5730\u5c06\u4e09\u4e2a\u6570\u636e\u6210\u5458\u4ea4\u6362\u4e86\u4e00\u4e0b\uff0c\u8fd9\u662f\u6b63\u786e\u7684\uff0c\u56e0\u4e3a\u5b83\u4eec\u5b58\u50a8\u7684\u90fd\u662fPOD\u7c7b\u578b\u3002\u6211\u8ba4\u4e3a\uff0c\u8fd9\u4e2a\u5b9e\u73b0\u5bf9\u51fd\u6570\u5bf9\u8c61\u5b58\u50a8\u5728\u672c\u5730\u7684\u6761\u4ef6\u7684\u9650\u5236\u592a\u8fc7\u4e25\u683c\uff0c\u5927\u5c0f\u5408\u9002\u7684\u53eftrivial\u590d\u5236\u7684\u51fd\u6570\u5bf9\u8c61\u4e5f\u5e94\u8be5\u53ef\u4ee5\u5b58\u50a8\u5728\u672c\u5730\u3002<\/p>\n<p>\u5728\u00a0<span class=\"cnblogs_code\">swap()<\/span>\u00a0\u7684\u57fa\u7840\u4e0a\uff0c\u62f7\u8d1d\u6784\u9020\u3001\u79fb\u52a8\u6784\u9020\u3001\u62f7\u8d1d\u8d4b\u503c\u3001\u79fb\u52a8\u8d4b\u503c\u51fd\u6570\u5f88\u81ea\u7136\u5730\u6784\u5efa\u8d77\u6765\u4e86\uff0c\u800c\u4e14\u53ea\u7528\u5230\u4e86\u00a0<span class=\"cnblogs_code\">swap()<\/span>\u00a0\u65b9\u6cd5\u3002\u8fd9\u79cd\u6280\u5de7\u79f0\u4e3a<a title=\"What is the copy-and-swap idiom?\" href=\"https:\/\/stackoverflow.com\/questions\/3279543\/what-is-the-copy-and-swap-idiom\" target=\"_blank\" rel=\"noopener noreferrer\">copy-and-swap<\/a>\u3002\u8fd9\u4e5f\u5c31\u89e3\u91ca\u4e86\u4e3a\u4ec0\u4e48\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u9700\u8981\u90a3\u4e48\u591a\u5ef6\u8fdf\u8c03\u7528\u7684\u64cd\u4f5c\u800c\u8868\u793a\u64cd\u4f5c\u7684\u679a\u4e3e\u7c7b\u53ea\u9700\u8981\u5b9a\u4e494\u79cd\u64cd\u4f5c\u3002<\/p>\n<p><span class=\"cnblogs_code\">swap()<\/span>\u00a0\u8fd8\u53ef\u4ee5\u6210\u4e3a\u5f02\u5e38\u5b89\u5168\u7684\u57fa\u7840\u3002\u7531\u4e8e\u4ee5\u4e0a\u65b9\u6cd5\u53ea\u6d89\u53ca\u5230\u00a0<span class=\"cnblogs_code\">swap()<\/span>\u00a0\uff0c\u800c\u00a0<span class=\"cnblogs_code\">swap()<\/span>\u00a0\u65b9\u6cd5\u662f\u4e0d\u629b\u5f02\u5e38\u7684\uff0c\u56e0\u6b64\u4e24\u4e2a\u79fb\u52a8\u51fd\u6570\u662f\u00a0<span class=\"cnblogs_code\">noexcept<\/span>\u00a0\u7684\uff0c\u4e24\u4e2a\u62f7\u8d1d\u51fd\u6570\u4e5f\u80fd\u4fdd\u8bc1\u5728\u6808\u7a7a\u95f4\u8db3\u591f\u65f6\u4e0d\u629b\u5f02\u5e38\uff0c\u5728\u629b\u5f02\u5e38\u65f6\u4e0d\u4f1a\u51fa\u73b0\u5185\u5b58\u6cc4\u6f0f\u3002<\/p>\n<p>\u5176\u4f59\u7684\u65b9\u6cd5\uff0c\u6709\u4e86\u524d\u9762\u7684\u57fa\u7840\uff0c\u770b\u4ee3\u7801\u5c31\u80fd\u8bfb\u61c2\u4e86\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_epilogue\"><\/a>\u540e\u8bb0<\/h3>\n<p>\u5199\u8fd9\u7bc7\u6587\u7ae0\u82b1\u4e86\u597d\u4e45\u5440\u3002\u8fd9\u662f\u6211\u7b2c\u4e00\u6b21\u5199\u8fd9\u4e48\u957f\u7684\u535a\u5ba2\uff0c\u5e0c\u671b\u4f60\u80fd\u6709\u6240\u6536\u83b7\u3002\u5982\u679c\u6709\u4e0d\u61c2\u7684\u5730\u65b9\uff0c\u53ef\u4ee5\u5728\u8bc4\u8bba\u533a\u7559\u8a00\u3002\u5982\u679c\u6709\u4efb\u4f55\u9519\u8bef\uff0c\u70e6\u8bf7\u6307\u6b63\u3002<\/p>\n<p>\u6211\u662f\u4ece\u5b9e\u73b0\u7684\u89d2\u5ea6\u6765\u5199\u7684\u8fd9\u7bc7\u6587\u7ae0\uff0c\u5982\u679c\u4f60\u5bf9\u5176\u4e2d\u7684\u4e00\u4e9b\u6280\u5de7\uff08SFINAE\u3001tag dispatching\uff09\u4e0d\u592a\u719f\u6089\u7684\u8bdd\uff0c\u7406\u89e3\u8d77\u6765\u53ef\u80fd\u6709\u70b9\u56f0\u96be\u3002<a title=\"std::function \u57fa\u672c\u5b9e\u73b0\" href=\"http:\/\/blog.bitfoc.us\/p\/525\" target=\"_blank\" rel=\"noopener noreferrer\">\u76f8\u5173\u8d44\u6599[8]<\/a>\u4ecb\u7ecd\u4e86\u00a0<span class=\"cnblogs_code\">function<\/span>\u00a0\u7c7b\u7684\u8bbe\u8ba1\u601d\u8def\uff0c\u4ece\u65e0\u5230\u6709\u7684\u6784\u5efa\u8fc7\u7a0b\u6bd4\u8f83\u5bb9\u6613\u7406\u89e3\u3002<a title=\"std::function \u6e90\u7801\u5206\u6790\" href=\"https:\/\/my.oschina.net\/u\/1866819\/blog\/614382\" target=\"_blank\" rel=\"noopener noreferrer\">\u76f8\u5173\u8d44\u6599[9]<\/a>\u5206\u6790\u4e86\u53e6\u4e00\u4e2a\u7248\u672c\u7684\u00a0<span class=\"cnblogs_code\">std::function<\/span>\u00a0\u5b9e\u73b0\uff0c\u53ef\u4f9b\u53c2\u8003\u3002<\/p>\n<p>\u6587\u7ae0\u5185\u5bb9\u5df2\u7ecf\u5f88\u5145\u5b9e\u4e86\uff0c\u4f46\u662f\u6ca1\u6709\u56fe\u7247\uff0c\u4e0d\u592a\u76f4\u89c2\u3002\u6709\u7a7a\u6211\u4f1a\u52a0\u4e0a\u56fe\u7247\u7684\uff0c\u8fd9\u6837\u66f4\u5bb9\u6613\u7406\u89e3\u3002<\/p>\n<p>\u53e6\u5916\uff0c\u5728\u6211\u5b9e\u73b0\u5b8c\u81ea\u5df1\u7684\u00a0<span class=\"cnblogs_code\">function<\/span>\u00a0\u7c7b\u4ee5\u540e\uff0c\u8fd8\u4f1a\u5bf9\u8fd9\u7bc7\u6587\u7ae0\u4f5c\u4e00\u70b9\u8865\u5145\u3002\u81ea\u5df1\u9020\u4e00\u904d\u8f6e\u5b50\uff0c\u603b\u4f1a\u6709\u66f4\u6df1\u523b\u7684\u611f\u53d7\u5427\u3002<\/p>\n<p>&nbsp;<\/p>\n<h3><a name=\"mark_appendix\"><\/a>\u9644\u5f55<\/h3>\n<p>\u76f8\u5173\u8d44\u6599\uff1a<\/p>\n<p>[1]\u00a0<a title=\"Naive std::function implementation\" href=\"https:\/\/shaharmike.com\/cpp\/naive-std-function\/\" target=\"_blank\" rel=\"noopener noreferrer\">Naive std::function implementation<\/a><\/p>\n<p>[2]\u00a0<a title=\"How is std::function implemented?\" href=\"https:\/\/stackoverflow.com\/questions\/18453145\/how-is-stdfunction-implemented\" target=\"_blank\" rel=\"noopener noreferrer\">How is std::function implemented?<br \/>\n<\/a><\/p>\n<p>[3]\u00a0<a title=\"std::function - cppreference.com\" href=\"https:\/\/en.cppreference.com\/w\/cpp\/utility\/functional\/function\" target=\"_blank\" rel=\"noopener noreferrer\">std::function &#8211; cppreference.com<\/a><\/p>\n<p>[4]\u00a0<a title=\"The space of design choices for std::function\" href=\"https:\/\/quuxplusone.github.io\/blog\/2019\/03\/27\/design-space-for-std-function\/\" target=\"_blank\" rel=\"noopener noreferrer\">The space of design choices for std::function<\/a><\/p>\n<p>[5]\u00a0<a title=\"How true is \u201cWant Speed? Pass by value\u201d\" href=\"https:\/\/stackoverflow.com\/questions\/21605579\/how-true-is-want-speed-pass-by-value\" target=\"_blank\" rel=\"noopener noreferrer\">How true is \u201cWant Speed? Pass by value\u201d<\/a><\/p>\n<p>[6]\u00a0<a title=\"C++\u5947\u6deb\u5de7\u6280\u4e4bSFINAE\" href=\"https:\/\/www.jianshu.com\/p\/45a2410d4085\" target=\"_blank\" rel=\"noopener noreferrer\">C++\u5947\u6deb\u5de7\u6280\u4e4bSFINAE<\/a><\/p>\n<p>[7]\u00a0<a title=\"What is the copy-and-swap idiom?\" href=\"https:\/\/stackoverflow.com\/questions\/3279543\/what-is-the-copy-and-swap-idiom\" target=\"_blank\" rel=\"noopener noreferrer\">What is the copy-and-swap idiom?<\/a><\/p>\n<p>[8]\u00a0<a title=\"std::function \u57fa\u672c\u5b9e\u73b0\" href=\"http:\/\/blog.bitfoc.us\/p\/525\" target=\"_blank\" rel=\"noopener noreferrer\">std::function \u57fa\u672c\u5b9e\u73b0<\/a><\/p>\n<p>[9]\u00a0<a title=\"std::function \u6e90\u7801\u5206\u6790\" href=\"https:\/\/my.oschina.net\/u\/1866819\/blog\/614382\" target=\"_blank\" rel=\"noopener noreferrer\">std::function \u6e90\u7801\u5206\u6790<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u539f\u6587\u5730\u5740 \u524d\u8a00 \u4e3a\u4ec0\u4e48\u8981\u5256\u6790\u00a0std::<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"colormag_page_container_layout":"default_layout","colormag_page_sidebar_layout":"default_layout","footnotes":""},"categories":[],"tags":[119],"class_list":["post-4637","post","type-post","status-publish","format-standard","hentry","tag-03-"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/4637","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/comments?post=4637"}],"version-history":[{"count":0,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/4637\/revisions"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=4637"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=4637"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=4637"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}