{"id":10008075,"date":"2023-07-11T13:00:13","date_gmt":"2023-07-11T05:00:13","guid":{"rendered":"https:\/\/ityet.com\/?p=10008075"},"modified":"2023-07-11T13:00:13","modified_gmt":"2023-07-11T05:00:13","slug":"go-defer-%e5%8e%bb%e6%8e%89%e9%97%ad%e5%8c%85%e5%87%bd%e6%95%b0%ef%bc%8c%e9%9d%a0%e8%b0%b1%e5%90%97%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10008075","title":{"rendered":"Go defer \u53bb\u6389\u95ed\u5305\u51fd\u6570\uff0c\u9760\u8c31\u5417\uff1f"},"content":{"rendered":"

\u5927\u5bb6\u597d\uff0c\u6211\u662f\u714e\u9c7c\u3002<\/p>\n

\u5728 Go \u8bed\u8a00\u91cc\uff0cdefer \u5173\u952e\u5b57\u662f\u5927\u5bb6\u5f88\u7231\u7528\u7684\u3002\u56e0\u4e3a\u4ed6\u6709\u7740 defer+recover+panic \u7684\u7ec4\u5408\u62f3\u6253\u6cd5\uff0c\u8fd8\u6709\u79cd\u5404\u79cd defer close \u7b49\u5e38\u7528\u573a\u666f\u3002<\/p>\n

defer \u5e38\u89c1\u7528\u6cd5<\/h2>\n

\u5728\u8bed\u6cd5\u4e0a\uff0cGo defer \u7684\u4ee3\u7801\u793a\u4f8b\u5982\u4e0b\uff1a<\/p>\n

package main\n\nimport "fmt"\n\nfunc main() {\n    defer fmt.Println("\u714e\u9c7c\u4f60\u597d\uff01")\n\n    fmt.Println("\u653e\u5b66\u522b\u8d70")\n}<\/code><\/pre>\n
\u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n
\u653e\u5b66\u522b\u8d70\n\u714e\u9c7c\u4f60\u597d\uff01<\/code><\/pre>\n
\u90a3 defer \u5728 Go \u91cc\u7684\u5e38\u89c1\u7528\u6cd5\u6709\u54ea\u4e9b\u5462\uff1f\u9996\u5148\u662f\u4e0a\u6587\u7528\u5230\u7684\uff0c\u76f4\u63a5 defer + \u51fd\u6570\uff1a<\/p>\n
defer f()<\/code><\/pre>\n
\u5176\u6b21\u662f defer+\u95ed\u5305\u7684\u65b9\u5f0f\uff1a<\/p>\n
defer func() { \n   result := f()\n   \/\/ do something with result\n}()<\/code><\/pre>\n
\u5176\u4ed6\u8fd8\u6709\u5728\u9762\u8bd5\u9898\u4e0a\u5e38\u88ab\u8003\u7a76\u7684\u4f20\u53c2\u53d8\u5f62\uff1a<\/p>\n
func f1() int {\n    i := 1\n    defer func() {\n        i++\n    }()\n    ...\n}\nfunc f2() int {\n    i := 1\n    defer func(i int) {\n        i++\n    }(i)\n    ....\n}<\/code><\/pre>\n
\u8fd9\u4e9b\u4ee3\u7801\u770b\u8d77\u6765\uff0c\u6211\u4eec\u603b\u662f\u5728\u5bf9 defer \u505a\u95ed\u5305\u7684\u5404\u79cd\u58f0\u660e\u548c\u4f7f\u7528\u3002defer \u4f1a\u4e0d\u4f1a\u5c31\u662f\u548c\u95ed\u5305\u5929\u751f\u4e00\u5bf9\uff1f<\/p>\n
\u65b0\u63d0\u6848\uff1adefer \u4ee3\u7801\u5757<\/h2>\n
\u6700\u8fd1\u5927\u5bb6\u4e5f\u5728\u8ba8\u8bba\u4e00\u4e2a\u4e0e\u4e4b\u76f8\u5173\u7684 Go \u63d0\u6848\u300aproposal: Go 2: deferred code blocks<\/a>\u300b\uff0c\u7531 @Damien Lloyd \u63d0\u51fa\uff0c\u60f3\u770b\u770b\u6709\u6ca1\u6709\u673a\u4f1a\u628a defer \u7684\u65b0\u8bed\u6cd5\u843d\u5730\u3002<\/p>\n
\"\"<\/p>\n
\u539f\u4f5c\u8005\u5728\u4f7f\u7528 defer \u65f6\u4e5f\u662f\u7ecf\u5e38\uff1a<\/p>\n
defer f()<\/code><\/pre>\n
\u4f46\u8fd9\u6837\u5c31\u65e0\u6cd5\u83b7\u5f97\u8fd4\u56de\u503c\u3002\u6700\u7ec8\u8981\u53d8\u6210\uff1a<\/p>\n
defer func() { \n   result := f()\n   \/\/ do something with result\n}()<\/code><\/pre>\n
\u57fa\u4e8e\u4e0a\u8ff0\u7c7b\u4f3c\u7684\u539f\u56e0\uff0c\u60f3\u5f15\u5165\u5982\u4e0b\u5177\u6709 defer \u4f5c\u7528\u7684\u4ee3\u7801\u5757\u8bed\u6cd5\uff1a<\/p>\n
defer {\n   \/\/ \u5728\u5c01\u95ed\u51fd\u6570\u7684\u672b\u5c3e\u6267\u884c\u6b64\u64cd\u4f5c\n}<\/code><\/pre>\n
\u5728\u4f7f\u7528\u4e86 defer \u5173\u952e\u5b57\u7684\u51fd\u6570\u6700\u540e\u6267\u884c\u8fd9\u6574\u4e2a\u4ee3\u7801\u5757 {...}<\/code>\u3002\u4ee3\u7801\u5757\u4e2d\u7684\u6bcf\u4e00\u884c\u5c06\u6309\u987a\u5e8f\u8fd0\u884c\u3002<\/p>\n
\u4f5c\u8005\u7ed9\u51fa\u7684\u4ee3\u7801\u793a\u4f8b\uff1a<\/p>\n
func fn() {\n    f, err := os.Create("eddycjy.txt")\n    if err != nil {\n        panic(err)\n    }\n\n    defer {\n       err := f.Close()\n\n       if err != nil {\n          panic(err)\n       }\n    }\n}<\/code><\/pre>\n
\u5728 fn \u51fd\u6570\uff0c\u58f0\u660e\u4e86 defer {...}<\/code>\uff0c\u4ee3\u7801\u5757\u5185\u662f\u5bf9 f.Close \u7684\u515c\u5e95\u5224\u65ad\u548c\u5f02\u5e38\u629b\u51fa\u3002\u5728\u51fd\u6570\u7ed3\u675f\u540e\u6267\u884c\u8fd9\u6574\u4e2a\u4ee3\u7801\u5757\u3002<\/p>\n
\u53cd\u5bf9\u7684\u58f0\u97f3<\/h2>\n
\u5f53\u7136\uff0c\u8fd9\u770b\u7740\u4f3c\u4e4e\u662f\u6bd4\u8f83\u7f8e\u597d\u7684\u3002\u770b\u8d77\u6765\u539f\u63d0\u6848\u4f5c\u8005\u53ea\u662f\u7b80\u5316\u4e86 defer \u662f\u7684\u95ed\u5305\u4f7f\u7528\uff0c\u8c03\u6574\u4e86\u4f5c\u7528\u57df\u7684\u8303\u56f4\u3002<\/p>\n
\u4f46\u5728\u793e\u533a\u5185\u5176\u5b9e\u906d\u53d7\u6bd4\u8f83\u591a\u7684\u53cd\u5bf9\u58f0\u97f3\u3002\u5305\u542b\u4f46\u4e0d\u9650\u4e8e\uff1a<\/p>\n
1\u3001\u6536\u76ca\u6bd4\u4e0d\u9ad8<\/strong>\uff1a\u8fd9\u4e2a\u63d0\u6848\u53ea\u662f\u907f\u514d\u4e86 func()<\/code> \u548c ()<\/code> \u7b49\u95ed\u5305\u58f0\u660e\uff0c\u4f46\u662f\u5374\u8981\u589e\u52a0\u65b0\u7684 defer \u8bed\u6cd5\uff08\u8bed\u8a00\u8bed\u6cd5\u66f4\u6539\u4f1a\u5e26\u6765\u9ad8\u6602\u6210\u672c\uff09\uff0c\u8fd9\u4e2a\u53d8\u66f4\u7684 ROI \u4e0d\u9ad8\u3002<\/p>\n
2\u3001\u7834\u574f\u517c\u5bb9\u6027<\/strong>\uff1a\u539f defer \u5173\u952e\u5b57\u8c03\u7528\u603b\u662f\u4f1a\u8ddf\u7740\u51fd\u6570\u7684\u8bcd\u6cd5\u8c03\u7528\uff0c\u6709\u826f\u597d\u7684\u4e00\u81f4\u6027\u3002\u5982\u679c\u8fdb\u884c\u4fee\u6539\uff0c\u4f1a\u4ea7\u751f\u65b0\u7684\u9690\u6666\uff0c\u7834\u574f\u4e00\u81f4\u6027\u3002\u4e5f\u4f1a\u5bf9\u73b0\u6709\u7684\u8bb8\u591a\u5de5\u5177\uff08\u4f8b\u5982\uff1a\u9759\u6001\u5206\u6790\u5de5\u5177\uff09\u4ea7\u751f\u5f71\u54cd\uff0c\u5168\u8981\u6539\u3002<\/p>\n
3\u3001\u4f5c\u7528\u57df\u95ee\u9898<\/strong>\uff1a\u539f\u672c defer func{}()<\/code> \u7684\u4ee3\u7801\u5757\u7ed3\u6784\u4e0b\uff0c\u4f60\u7684\u4ee3\u7801\u4f5c\u7528\u57df\u90fd\u9650\u4e8e\u95ed\u5305\u51fd\u6570\u4e0b\u3002\u800c\u4f7f\u7528\u65b0\u7684 defer {}<\/code> \u7684\u7ed3\u6784\uff0c\u8be5\u8fd4\u56de\u548c\u64cd\u4f5c\uff0c\u662f\u5426\u5e94\u8be5\u4f1a\u5f71\u54cd\u5230\u5916\u90e8\u51fd\u6570\u7684\u7ed3\u679c\uff1f\uff08\u8fd9\u662f\u6700\u6709\u4e89\u8bae\u7684\u4e00\u70b9\uff0c\u4f5c\u8005\u4e5f\u6bd4\u8f83\u524d\u8a00\u4e0d\u642d\u540e\u8bed\uff0c\u6ca1\u660e\u786e\u6307\u660e\u8bed\u6cd5\u610f\u601d\uff09<\/p>\n
\u603b\u7ed3<\/h2>\n
\u4e00\u5f00\u59cb\u4e4d\u4e00\u773c\u4e00\u770b\uff0c\u611f\u89c9\u53ea\u662f\u628a defer \u5173\u952e\u5b57\u8bed\u53e5\u7b80\u5316\u4e00\u4e0b\uff0c\u597d\u50cf\u7279\u522b\u597d\uff0c\u7701\u4e86\u51e0\u4e2a\u5355\u8bcd\u3002\u5c31\u50cf if err != nil<\/code> \u4e5f\u4f1a\u6709\u63d0\u8981\u7528 Rust \u7684 ?<\/code> \u7b49\u7528\u6cd5\u6765\u66ff\u4ee3\u7684\u3002<\/p>\n
\u7ecf\u8fc7\u793e\u533a\u7f51\u53cb\u4eec\u6307\u51fa\u540e\uff0c\u53d1\u73b0\u8fd9\u91cc\u732b\u817b\u4e0d\u5c11\u3002\u4e00\u95e8\u5df2\u7ecf\u6709 10+ \u5e74\u7684\u7f16\u7a0b\u8bed\u8a00\uff0c\u8fd8\u6709 Go1 \u517c\u5bb9\u6027\u4fdd\u969c\u7684\u3002\u505a\u51fa\u8fd9\u7c7b\u5e26\u4f5c\u7528\u57df\u7684\u63d0\u6848\u53d8\u66f4\uff0c\u662f\u6709\u6bd4\u8f83\u5927\u7684\u98ce\u9669\u7684\u3002<\/p>\n
\u540c\u65f6\u5bf9\u4e8e Go \u5de5\u5177\u94fe\u7684\u5f71\u54cd\uff0c\u4e5f\u662f\u975e\u5e38\u5927\u7684\u3002\u4e00\u6539\uff0c\u76f4\u63a5\u90fd\u5b8c\u728a\u5b50\u4e86\u3002\u786e\u5b9e\u9700\u8981\u5c3d\u91cf\u6df1\u601d\u3002\u539f\u4f5c\u8005\u5b8c\u5168\u6ca1\u63d0\u5230\u3002<\/p>\n
\u8be5\u63d0\u6848\uff0c\u6b63\u5728\u5f00\u653e 3 \u5468\u7b49\u5f85\u610f\u89c1\u6536\u96c6\u3002\u5f88\u795e\u5947\uff0c\u6ca1\u66f4\u591a\u7684\u4eba\u8bf4\u8bdd\uff0c\u4f46\u63d0\u6848\u7684\u8868\u60c5\u7ed9\u4e86\u5f88\u591a\u4e2a\u4e0d\u8ba4\u540c\u3002<\/p>\n
\"\"<\/p>\n
\u63a8\u8350\u9605\u8bfb<\/h4>\n