{"id":7427,"date":"2026-07-22T12:10:35","date_gmt":"2026-07-22T04:10:35","guid":{"rendered":"https:\/\/i007.cc\/wordpress\/?p=7427"},"modified":"2026-07-22T12:10:35","modified_gmt":"2026-07-22T04:10:35","slug":"%e8%af%a6%e8%a7%a3lambda%e8%a1%a8%e8%be%be%e5%bc%8f%e7%9a%84%e6%8d%95%e8%8e%b7","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/7427","title":{"rendered":"\u8be6\u89e3Lambda\u8868\u8fbe\u5f0f\u7684\u6355\u83b7"},"content":{"rendered":"

\u8fd9\u6bb5\u4ee3\u7801\u6211\u4e4b\u524d\u7ed9\u4f60\u5199\u7684\u4f8b\u5b50\u662f\u5bf9\u7684\uff0c\u6211\u6765\u786e\u8ba4\u4e00\u4e0b\u5176\u4e2d\u7684\u5173\u952e\u70b9\uff0c\u786e\u4fdd\u4f60\u5b8c\u5168\u7406\u89e3 \u2705<\/p>\n

\n

\u9010\u884c\u89e3\u91ca<\/h3>\n
\n
\n
<\/div>\n<\/div>\n
cpp<\/div>\n
\n
int count = 0;\r\n\r\nauto counter = [count]() mutable {\r\n    count++;\r\n    return count;\r\n};<\/pre>\n
 <\/p>\n<\/div>\n<\/div>\n
    \n
  • [count]<\/code> \u2014\u2014 \u503c\u6355\u83b7<\/strong>\uff1a\u5728 Lambda \u5b9a\u4e49\u7684\u90a3\u4e00\u523b<\/strong>\uff0c\u628a count<\/code> \u7684\u503c\uff080\uff09\u62f7\u8d1d\u4e86\u4e00\u4efd\uff0c\u5b58\u5728 Lambda \u5bf9\u8c61\u5185\u90e8\u3002<\/li>\n
  • mutable<\/code> \u2014\u2014 \u9ed8\u8ba4\u503c\u6355\u83b7\u7684\u526f\u672c\u662f const<\/code> \u7684\uff0c\u4e0d\u80fd\u4fee\u6539\u3002\u52a0\u4e0a mutable<\/code> \u540e\uff0c\u8fd9\u4e2a\u526f\u672c\u53d8\u5f97\u53ef\u4fee\u6539<\/strong>\u3002<\/li>\n
  • \u8fd9\u4e2a\u526f\u672c\u548c\u5916\u90e8\u7684 count<\/code> \u4ece\u6b64\u518d\u65e0\u5173\u7cfb<\/strong>\u2014\u2014\u662f\u5b8c\u5168\u72ec\u7acb\u7684\u4e24\u5757\u5185\u5b58\u3002<\/li>\n<\/ul>\n
    \n
    \u8c03\u7528\u8fc7\u7a0b<\/h3>\n
    \n
    \n
    <\/div>\n<\/div>\n
    cpp<\/div>\n
    \n
    counter();  \/\/ \u5185\u90e8\u526f\u672c\uff1a0 \u2192 1\uff0c\u8fd4\u56de 1\r\ncounter();  \/\/ \u5185\u90e8\u526f\u672c\uff1a1 \u2192 2\uff0c\u8fd4\u56de 2\uff08\u6ce8\u610f\uff1a\u526f\u672c\u7684\u72b6\u6001\u88ab\"\u8bb0\u4f4f\"\u4e86\uff01\uff09\r\n\r\ncount;      \/\/ \u5916\u90e8\u7684 count \u4ecd\u662f 0<\/pre>\n
     <\/p>\n<\/div>\n<\/div>\n
    \u5173\u952e\u70b9<\/strong>\uff1aLambda \u5bf9\u8c61\u5185\u90e8\u7684 count<\/code> \u526f\u672c\uff0c\u5728\u591a\u6b21\u8c03\u7528\u4e4b\u95f4\u662f\u6301\u7eed\u5b58\u5728\u7684<\/strong>\uff08\u56e0\u4e3a\u5b83\u5b58\u50a8\u5728 Lambda \u5bf9\u8c61\u672c\u8eab\u91cc\uff0c\u4e0d\u662f\u6bcf\u6b21\u8c03\u7528\u91cd\u65b0\u521d\u59cb\u5316\uff09\u3002\u6240\u4ee5\uff1a<\/p>\n
    \n
    \n
    <\/div>\n<\/div>\n
    cpp<\/div>\n
    \n
    counter() \u7b2c\u4e00\u6b21\u8c03\u7528 \u2192 \u526f\u672c0+1=1\r\ncounter() \u7b2c\u4e8c\u6b21\u8c03\u7528 \u2192 \u526f\u672c1+1=2\uff08\u57fa\u4e8e\u4e0a\u6b21\u7ed3\u679c\u7d2f\u52a0\uff09<\/pre>\n
     <\/p>\n<\/div>\n<\/div>\n
    \u8fd9\u5176\u5b9e\u8ba9 counter<\/code> \u53d8\u6210\u4e86\u4e00\u4e2a\u5e26\u72b6\u6001\u7684\u8ba1\u6570\u5668<\/strong>\uff0c\u5f88\u50cf\u4e00\u4e2a\u5fae\u578b\u7684”\u95ed\u5305\u5bf9\u8c61”\u3002<\/p>\n
    \n
    \u53ef\u89c6\u5316\u5185\u5b58\u56fe<\/h3>\n
    \n
    \n
    <\/div>\n<\/div>\n
    \n
    \u5b9a\u4e49\u65f6\uff1a\r\n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510         \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\r\n\u2502 \u5916\u90e8 count=0 \u2502         \u2502 Lambda\u5bf9\u8c61   \u2502\r\n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518         \u2502  \u5185\u90e8\u526f\u672c=0  \u2502 \u2190 mutable\uff0c\u53ef\u6539\r\n                         \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518\r\n\r\n\u8c03\u7528\u4e24\u6b21\u540e\uff1a\r\n\u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510         \u250c\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2510\r\n\u2502 \u5916\u90e8 count=0 \u2502 (\u4e0d\u53d8)   \u2502 Lambda\u5bf9\u8c61   \u2502\r\n\u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518         \u2502  \u5185\u90e8\u526f\u672c=2  \u2502 \u2190 \u7d2f\u8ba1\u53d8\u5316\r\n                         \u2514\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2500\u2518<\/pre>\n
     <\/p>\n<\/div>\n<\/div>\n
    \n
    \u9a8c\u8bc1\u4e00\u4e0b\uff1a\u5982\u679c\u4e0d\u52a0 mutable<\/code> \u4f1a\u600e\u6837\uff1f<\/h3>\n
    \n
    \n
    <\/div>\n<\/div>\n
    cpp<\/div>\n
    \n
    auto counter = [count]() {\r\n    count++;   \/\/ \u274c \u7f16\u8bd1\u9519\u8bef\uff01\r\n    return count;\r\n};<\/pre>\n
     <\/p>\n<\/div>\n<\/div>\n
    \u62a5\u9519\u5927\u81f4\u662f\uff1a<\/p>\n
    \n
    \n
    <\/div>\n<\/div>\n
    \n
    error: increment of read-only variable 'count'<\/pre>\n
     <\/p>\n<\/div>\n<\/div>\n
    \u56e0\u4e3a\u6ca1\u6709 mutable<\/code>\uff0c\u503c\u6355\u83b7\u7684\u526f\u672c\u9ed8\u8ba4\u662f const int count<\/code>\uff0c\u4e0d\u5141\u8bb8\u4fee\u6539\u3002<\/p>\n
    \n
    \u8fd9\u4e2a\u7528\u6cd5\u5b9e\u9645\u6709\u4ec0\u4e48\u7528\uff1f<\/h3>\n
    \n
    \n
    <\/div>\n<\/div>\n
    cpp<\/div>\n
    \n
    \/\/ \u751f\u6210\u4e00\u4e2a\u72ec\u7acb\u8ba1\u6570\u5668\uff0c\u6bcf\u6b21\u8c03\u7528\u81ea\u589e\r\nauto makeCounter = []() {\r\n    int id = 0;\r\n    return [id]() mutable {\r\n        return ++id;\r\n    };\r\n};\r\n\r\nauto counterA = makeCounter();\r\nauto counterB = makeCounter();\r\n\r\ncounterA();  \/\/ 1\r\ncounterA();  \/\/ 2\r\ncounterB();  \/\/ 1\uff08counterB \u6709\u81ea\u5df1\u72ec\u7acb\u7684\u526f\u672c\uff0c\u4e92\u4e0d\u5f71\u54cd\uff01\uff09<\/pre>\n
     <\/p>\n<\/div>\n<\/div>\n
    \u8fd9\u5176\u5b9e\u5c31\u662f\u7528 Lambda \u5b9e\u73b0\u4e86\u4e00\u4e2a\u8f7b\u91cf\u7ea7\u7684\u95ed\u5305\u5de5\u5382<\/strong>\uff0c\u6bcf\u4e2a Lambda \u5b9e\u4f8b\u90fd\u6709\u81ea\u5df1\u72ec\u7acb\u7684\u72b6\u6001\u3002<\/p>\n
    \u4f60\u7684\u7406\u89e3\u5b8c\u5168\u6b63\u786e\uff01\u6709\u4ec0\u4e48\u5177\u4f53\u7591\u95ee\uff0c\u8fd8\u662f\u60f3\u770b\u66f4\u591a mutable<\/code> \u7684\u5e94\u7528\u573a\u666f\uff1f<\/p>\n","protected":false},"excerpt":{"rendered":"
    \u8fd9\u6bb5\u4ee3\u7801\u6211\u4e4b\u524d\u7ed9\u4f60\u5199\u7684\u4f8b\u5b50\u662f\u5bf9\u7684\uff0c\u6211\u6765\u786e<\/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":[24],"tags":[],"class_list":["post-7427","post","type-post","status-publish","format-standard","hentry","category-value_docs"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7427","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=7427"}],"version-history":[{"count":1,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7427\/revisions"}],"predecessor-version":[{"id":7428,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7427\/revisions\/7428"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=7427"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=7427"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=7427"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}