{"id":2635,"date":"2019-01-02T08:09:38","date_gmt":"2019-01-02T00:09:38","guid":{"rendered":"https:\/\/damogame.cn:15443\/wordpress\/?p=2635"},"modified":"2019-01-02T08:09:38","modified_gmt":"2019-01-02T00:09:38","slug":"go%e8%af%ad%e8%a8%80-%e5%85%b3%e9%94%ae%e5%ad%97%ef%bc%9adefer","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/2635","title":{"rendered":"Go\u8bed\u8a00 \u5173\u952e\u5b57\uff1adefer"},"content":{"rendered":"<div id=\"pro-mian-header\">\n<div class=\"content-top\"><\/div>\n<div class=\"kn-infomation\">defer\u548cgo\u4e00\u6837\u90fd\u662fGo\u8bed\u8a00\u63d0\u4f9b\u7684\u5173\u952e\u5b57\u3002defer\u7528\u4e8e\u8d44\u6e90\u7684\u91ca\u653e\uff0c\u4f1a\u5728\u51fd\u6570\u8fd4\u56de\u4e4b\u524d\u8fdb\u884c\u8c03\u7528\u3002\u4e00\u822c\u91c7\u7528\u5982\u4e0b\u6a21\u5f0f\uff1a<\/div>\n<\/div>\n<div class=\"content-bg\">\n<div class=\"content-intro view-box \">\n<section>\n<pre><code class=\"hljs ruby\">f,err <span class=\"hljs-symbol\">:<\/span>= os.Open(filename)\r\n<span class=\"hljs-keyword\">if<\/span> err != <span class=\"hljs-literal\">nil<\/span> {\r\n    panic(err)\r\n}\r\ndefer f.Close()\r\n<\/code><\/pre>\n<p>\u5982\u679c\u6709\u591a\u4e2adefer\u8868\u8fbe\u5f0f\uff0c\u8c03\u7528\u987a\u5e8f\u7c7b\u4f3c\u4e8e\u6808\uff0c\u8d8a\u540e\u9762\u7684defer\u8868\u8fbe\u5f0f\u8d8a\u5148\u88ab\u8c03\u7528\u3002<\/p>\n<p>\u4e0d\u8fc7\u5982\u679c\u5bf9defer\u7684\u4e86\u89e3\u4e0d\u591f\u6df1\u5165\uff0c\u4f7f\u7528\u8d77\u6765\u53ef\u80fd\u4f1a\u8e29\u5230\u4e00\u4e9b\u5751\uff0c\u5c24\u5176\u662f\u8ddf\u5e26\u547d\u540d\u7684\u8fd4\u56de\u53c2\u6570\u4e00\u8d77\u4f7f\u7528\u65f6\u3002\u5728\u8bb2\u89e3defer\u7684\u5b9e\u73b0\u4e4b\u524d\u5148\u770b\u4e00\u770b\u4f7f\u7528defer\u5bb9\u6613\u9047\u5230\u7684\u95ee\u9898\u3002<\/p>\n<h2>defer\u4f7f\u7528\u65f6\u7684\u5751<\/h2>\n<p>\u5148\u6765\u770b\u770b\u51e0\u4e2a\u4f8b\u5b50\u3002\u4f8b1\uff1a<\/p>\n<pre><code class=\"hljs cpp\"><span class=\"hljs-function\">func <span class=\"hljs-title\">f<\/span><span class=\"hljs-params\">()<\/span> <span class=\"hljs-params\">(result <span class=\"hljs-keyword\">int<\/span>)<\/span> <\/span>{\r\n    <span class=\"hljs-function\">defer <span class=\"hljs-title\">func<\/span><span class=\"hljs-params\">()<\/span> <\/span>{\r\n        result++\r\n    }()\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-number\">0<\/span>\r\n}\r\n<\/code><\/pre>\n<p>\u4f8b2\uff1a<\/p>\n<pre><code class=\"hljs css\"><span class=\"hljs-selector-tag\">func<\/span> <span class=\"hljs-selector-tag\">f<\/span>() (<span class=\"hljs-selector-tag\">r<\/span> <span class=\"hljs-selector-tag\">int<\/span>) {\r\n     <span class=\"hljs-attribute\">t <\/span>:= <span class=\"hljs-number\">5<\/span>\r\n     defer <span class=\"hljs-built_in\">func<\/span>() {\r\n       t = t + <span class=\"hljs-number\">5<\/span>\r\n     }()\r\n     <span class=\"hljs-selector-tag\">return<\/span> <span class=\"hljs-selector-tag\">t<\/span>\r\n}\r\n<\/code><\/pre>\n<p>\u4f8b3\uff1a<\/p>\n<pre><code class=\"hljs cpp\"><span class=\"hljs-function\">func <span class=\"hljs-title\">f<\/span><span class=\"hljs-params\">()<\/span> <span class=\"hljs-params\">(r <span class=\"hljs-keyword\">int<\/span>)<\/span> <\/span>{\r\n    <span class=\"hljs-function\">defer <span class=\"hljs-title\">func<\/span><span class=\"hljs-params\">(r <span class=\"hljs-keyword\">int<\/span>)<\/span> <\/span>{\r\n          r = r + <span class=\"hljs-number\">5<\/span>\r\n    }(r)\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-number\">1<\/span>\r\n}\r\n<\/code><\/pre>\n<p>\u8bf7\u8bfb\u8005\u5148\u4e0d\u8981\u8fd0\u884c\u4ee3\u7801\uff0c\u5728\u5fc3\u91cc\u8dd1\u4e00\u904d\u7ed3\u679c\uff0c\u7136\u540e\u53bb\u9a8c\u8bc1\u3002<\/p>\n<p>\u4f8b1\u7684\u6b63\u786e\u7b54\u6848\u4e0d\u662f0\uff0c\u4f8b2\u7684\u6b63\u786e\u7b54\u6848\u4e0d\u662f10\uff0c\u5982\u679c\u4f8b3\u7684\u6b63\u786e\u7b54\u6848\u4e0d\u662f6&#8230;&#8230;<\/p>\n<p>defer\u662f\u5728return\u4e4b\u524d\u6267\u884c\u7684\u3002\u8fd9\u4e2a\u5728\u00a0<a href=\"http:\/\/golang.org\/ref\/spec#defer_statements\" target=\"_blank\" rel=\"noopener\">\u5b98\u65b9\u6587\u6863<\/a>\u4e2d\u662f\u660e\u786e\u8bf4\u660e\u4e86\u7684\u3002\u8981\u4f7f\u7528defer\u65f6\u4e0d\u8e29\u5751\uff0c\u6700\u91cd\u8981\u7684\u4e00\u70b9\u5c31\u662f\u8981\u660e\u767d\uff0c<strong>return xxx\u8fd9\u4e00\u6761\u8bed\u53e5\u5e76\u4e0d\u662f\u4e00\u6761\u539f\u5b50\u6307\u4ee4!<\/strong><\/p>\n<p>\u51fd\u6570\u8fd4\u56de\u7684\u8fc7\u7a0b\u662f\u8fd9\u6837\u7684\uff1a\u5148\u7ed9\u8fd4\u56de\u503c\u8d4b\u503c\uff0c\u7136\u540e\u8c03\u7528defer\u8868\u8fbe\u5f0f\uff0c\u6700\u540e\u624d\u662f\u8fd4\u56de\u5230\u8c03\u7528\u51fd\u6570\u4e2d\u3002<\/p>\n<p>defer\u8868\u8fbe\u5f0f\u53ef\u80fd\u4f1a\u5728\u8bbe\u7f6e\u51fd\u6570\u8fd4\u56de\u503c\u4e4b\u540e\uff0c\u5728\u8fd4\u56de\u5230\u8c03\u7528\u51fd\u6570\u4e4b\u524d\uff0c\u4fee\u6539\u8fd4\u56de\u503c\uff0c\u4f7f\u6700\u7ec8\u7684\u51fd\u6570\u8fd4\u56de\u503c\u4e0e\u4f60\u60f3\u8c61\u7684\u4e0d\u4e00\u81f4\u3002<\/p>\n<p>\u5176\u5b9e\u4f7f\u7528defer\u65f6\uff0c\u7528\u4e00\u4e2a\u7b80\u5355\u7684\u8f6c\u6362\u89c4\u5219\u6539\u5199\u4e00\u4e0b\uff0c\u5c31\u4e0d\u4f1a\u8ff7\u7cca\u4e86\u3002\u6539\u5199\u89c4\u5219\u662f\u5c06return\u8bed\u53e5\u62c6\u6210\u4e24\u53e5\u5199\uff0creturn xxx\u4f1a\u88ab\u6539\u5199\u6210:<\/p>\n<pre><code class=\"hljs javascript\">\u8fd4\u56de\u503c = xxx\r\n\u8c03\u7528defer\u51fd\u6570\r\n\u7a7a\u7684<span class=\"hljs-keyword\">return<\/span>\r\n<\/code><\/pre>\n<p>\u5148\u770b\u4f8b1\uff0c\u5b83\u53ef\u4ee5\u6539\u5199\u6210\u8fd9\u6837\uff1a<\/p>\n<pre><code class=\"hljs cpp\"><span class=\"hljs-function\">func <span class=\"hljs-title\">f<\/span><span class=\"hljs-params\">()<\/span> <span class=\"hljs-params\">(result <span class=\"hljs-keyword\">int<\/span>)<\/span> <\/span>{\r\n     result = <span class=\"hljs-number\">0<\/span>  <span class=\"hljs-comment\">\/\/return\u8bed\u53e5\u4e0d\u662f\u4e00\u6761\u539f\u5b50\u8c03\u7528\uff0creturn xxx\u5176\u5b9e\u662f\u8d4b\u503c\uff0bret\u6307\u4ee4<\/span>\r\n     func() { <span class=\"hljs-comment\">\/\/defer\u88ab\u63d2\u5165\u5230return\u4e4b\u524d\u6267\u884c\uff0c\u4e5f\u5c31\u662f\u8d4b\u8fd4\u56de\u503c\u548cret\u6307\u4ee4\u4e4b\u95f4<\/span>\r\n         result++\r\n     }()\r\n     <span class=\"hljs-keyword\">return<\/span>\r\n}\r\n<\/code><\/pre>\n<p>\u6240\u4ee5\u8fd9\u4e2a\u8fd4\u56de\u503c\u662f1\u3002<\/p>\n<p>\u518d\u770b\u4f8b2\uff0c\u5b83\u53ef\u4ee5\u6539\u5199\u6210\u8fd9\u6837\uff1a<\/p>\n<pre><code class=\"hljs cpp\"><span class=\"hljs-function\">func <span class=\"hljs-title\">f<\/span><span class=\"hljs-params\">()<\/span> <span class=\"hljs-params\">(r <span class=\"hljs-keyword\">int<\/span>)<\/span> <\/span>{\r\n     t := <span class=\"hljs-number\">5<\/span>\r\n     r = t <span class=\"hljs-comment\">\/\/\u8d4b\u503c\u6307\u4ee4<\/span>\r\n     func() {        <span class=\"hljs-comment\">\/\/defer\u88ab\u63d2\u5165\u5230\u8d4b\u503c\u4e0e\u8fd4\u56de\u4e4b\u95f4\u6267\u884c\uff0c\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\u8fd4\u56de\u503cr\u6ca1\u88ab\u4fee\u6539\u8fc7<\/span>\r\n         t = t + <span class=\"hljs-number\">5<\/span>\r\n     }\r\n     <span class=\"hljs-keyword\">return<\/span>        <span class=\"hljs-comment\">\/\/\u7a7a\u7684return\u6307\u4ee4<\/span>\r\n}\r\n<\/code><\/pre>\n<p>\u6240\u4ee5\u8fd9\u4e2a\u7684\u7ed3\u679c\u662f5\u3002<\/p>\n<p>\u6700\u540e\u770b\u4f8b3\uff0c\u5b83\u6539\u5199\u540e\u53d8\u6210\uff1a<\/p>\n<pre><code class=\"hljs cpp\"><span class=\"hljs-function\">func <span class=\"hljs-title\">f<\/span><span class=\"hljs-params\">()<\/span> <span class=\"hljs-params\">(r <span class=\"hljs-keyword\">int<\/span>)<\/span> <\/span>{\r\n     r = <span class=\"hljs-number\">1<\/span>  <span class=\"hljs-comment\">\/\/\u7ed9\u8fd4\u56de\u503c\u8d4b\u503c<\/span>\r\n     func(r <span class=\"hljs-keyword\">int<\/span>) {        <span class=\"hljs-comment\">\/\/\u8fd9\u91cc\u6539\u7684r\u662f\u4f20\u503c\u4f20\u8fdb\u53bb\u7684r\uff0c\u4e0d\u4f1a\u6539\u53d8\u8981\u8fd4\u56de\u7684\u90a3\u4e2ar\u503c<\/span>\r\n          r = r + <span class=\"hljs-number\">5<\/span>\r\n     }(r)\r\n     <span class=\"hljs-keyword\">return<\/span>        <span class=\"hljs-comment\">\/\/\u7a7a\u7684return<\/span>\r\n}\r\n<\/code><\/pre>\n<p>\u6240\u4ee5\u8fd9\u4e2a\u4f8b\u5b50\u7684\u7ed3\u679c\u662f1\u3002<\/p>\n<p>defer\u786e\u5b9e\u662f\u5728return\u4e4b\u524d\u8c03\u7528\u7684\u3002\u4f46\u8868\u73b0\u5f62\u5f0f\u4e0a\u5374\u53ef\u80fd\u4e0d\u50cf\u3002\u672c\u8d28\u539f\u56e0\u662freturn xxx\u8bed\u53e5\u5e76\u4e0d\u662f\u4e00\u6761\u539f\u5b50\u6307\u4ee4\uff0cdefer\u88ab\u63d2\u5165\u5230\u4e86\u8d4b\u503c \u4e0e ret\u4e4b\u95f4\uff0c\u56e0\u6b64\u53ef\u80fd\u6709\u673a\u4f1a\u6539\u53d8\u6700\u7ec8\u7684\u8fd4\u56de\u503c\u3002<\/p>\n<h2>defer\u7684\u5b9e\u73b0<\/h2>\n<p>defer\u5173\u952e\u5b57\u7684\u5b9e\u73b0\u8ddfgo\u5173\u952e\u5b57\u5f88\u7c7b\u4f3c\uff0c\u4e0d\u540c\u7684\u662f\u5b83\u8c03\u7528\u7684\u662fruntime.deferproc\u800c\u4e0d\u662fruntime.newproc\u3002<\/p>\n<p>\u5728defer\u51fa\u73b0\u7684\u5730\u65b9\uff0c\u63d2\u5165\u4e86\u6307\u4ee4call runtime.deferproc\uff0c\u7136\u540e\u5728\u51fd\u6570\u8fd4\u56de\u4e4b\u524d\u7684\u5730\u65b9\uff0c\u63d2\u5165\u6307\u4ee4call runtime.deferreturn\u3002<\/p>\n<p>\u666e\u901a\u7684\u51fd\u6570\u8fd4\u56de\u65f6\uff0c\u6c47\u7f16\u4ee3\u7801\u7c7b\u4f3c\uff1a<\/p>\n<pre><code class=\"hljs javascript\">add xx SP\r\n<span class=\"hljs-keyword\">return<\/span>\r\n<\/code><\/pre>\n<p>\u5982\u679c\u5176\u4e2d\u5305\u542b\u4e86defer\u8bed\u53e5\uff0c\u5219\u6c47\u7f16\u4ee3\u7801\u662f\uff1a<\/p>\n<pre><code class=\"hljs sql\"><span class=\"hljs-keyword\">call<\/span> runtime.deferreturn\uff0c\r\n<span class=\"hljs-keyword\">add<\/span> xx SP\r\n<span class=\"hljs-keyword\">return<\/span>\r\n<\/code><\/pre>\n<p>goroutine\u7684\u63a7\u5236\u7ed3\u6784\u4e2d\uff0c\u6709\u4e00\u5f20\u8868\u8bb0\u5f55defer\uff0c\u8c03\u7528runtime.deferproc\u65f6\u4f1a\u5c06\u9700\u8981defer\u7684\u8868\u8fbe\u5f0f\u8bb0\u5f55\u5728\u8868\u4e2d\uff0c\u800c\u5728\u8c03\u7528runtime.deferreturn\u7684\u65f6\u5019\uff0c\u5219\u4f1a\u4f9d\u6b21\u4ecedefer\u8868\u4e2d\u51fa\u6808\u5e76\u6267\u884c\u3002<\/p>\n<\/section>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>defer\u548cgo\u4e00\u6837\u90fd\u662fGo\u8bed\u8a00\u63d0\u4f9b\u7684\u5173<\/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":[122],"class_list":["post-2635","post","type-post","status-publish","format-standard","hentry","tag-06-godocker"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/2635","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=2635"}],"version-history":[{"count":0,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/2635\/revisions"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=2635"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=2635"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=2635"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}