{"id":10006722,"date":"2022-10-24T16:00:39","date_gmt":"2022-10-24T08:00:39","guid":{"rendered":"https:\/\/ityet.com\/?p=10006722"},"modified":"2022-10-24T16:00:39","modified_gmt":"2022-10-24T08:00:39","slug":"go-try-%e6%96%b0%e6%8f%90%e6%a1%88%e9%9d%a0%e8%b0%b1%e5%90%97%ef%bc%9f%e6%83%b3%e7%ae%80%e5%8c%96%e9%94%99%e8%af%af%e5%a4%84%e7%90%86%e4%ba%86","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10006722","title":{"rendered":"Go try \u65b0\u63d0\u6848\u9760\u8c31\u5417\uff1f\u60f3\u7b80\u5316\u9519\u8bef\u5904\u7406\u4e86"},"content":{"rendered":"

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

\u5728\u8fd1\u65e5\u65b0\u7684 try \u63d0\u6848\u300aproposal: Go 2: error handling: try statement with handler<\/a>\u300b\u5728\u793e\u533a\u5f15\u53d1\u4e86\u70ed\u8bae\u3002<\/p>\n

\u4eca\u5929\u714e\u9c7c\u548c\u5927\u5bb6\u4e00\u8d77\u6253\u5f00\u6765\u770b\u770b\uff0c\u8fd9\u80fd\u628a Go \u9519\u8bef\u5904\u7406\u673a\u5236\u7ed9\u6380\u5f00\u91cd\u6574\u4e0d\u3002<\/p>\n

\u80cc\u666f<\/h2>\n

\u6765\u81ea PingCAP \u7684\u63d0\u6848\u4f5c\u8005 @Greg Weber \u4f1a\u5e72\u8fd9\u4e8b\u57fa\u4e8e\u4e24\u4e2a\u56e0\u7d20\uff0c\u4e00\u4e2a\u662f\u5728\u300aGo Developer Survey 2022 Q2 Results<\/a>\u300b\u4e2d\u660e\u786e\u63d0\u5230\u3002<\/p>\n

\"\"<\/p>\n

\u968f\u7740 Go1.18 \u6cdb\u578b\u7684\u53d1\u5e03\uff0c\u539f\u5148\u77db\u76fe\u6700\u6df1\u7684\u6cdb\u578b\u5df2\u7ecf\u5f97\u5230\u4e00\u4e2a\u521d\u6b65\u7684\u89e3\u51b3\u65b9\u6848\u3002\u5728\u793e\u533a\u8c03\u7814\u4e0a\uff0c\u5f00\u53d1\u8005\u5728\u4f7f\u7528 Go \u65f6\u9762\u4e34\u7684\u6700\u5927\u6311\u6218\u5df2\u7ecf\u8f6c\u79fb\u5230\u4e86\u9519\u8bef\u5904\u7406\u4e0a\uff0c\u9700\u8981\u6295\u5165\u7cbe\u529b\u53bb \u201c\u89e3\u51b3\u201d \u5b83\u3002<\/p>\n

\u53e6\u5916\u4e00\u4e2a\u56e0\u7d20\u5c31\u662f\u4f17\u6240\u7686\u77e5\u7684\uff0cGo \u9519\u8bef\u5904\u7406\u4ee3\u7801\u6bd4\u8f83\u7e41\u7410\uff0c\u5e38\u88ab\u5de5\u7a0b\u5e08\u4eec\u620f\u79f0\u4e00\u4e2a Go \u5de5\u7a0b\u91cc\u6709 30% \u90fd if err = nil\u3002<\/p>\n

\u5982\u4e0b\u4ee3\u7801\uff1a<\/p>\n

_, err := f()\nif err != nil {\n    ...\n}\n_, err = r()\nif err != nil {\n    ...\n}\n_, err = w()\nif err != nil {\n    ...\n}<\/code><\/pre>\n
\u5e0c\u671b\u8ba9\u5176\u66f4\u4f18\u96c5\u3002\u4e5f\u6709\u8bb8\u591a\u5c0f\u4f19\u4f34\u8ba4\u540c\u8fd9\u4e2a\u8bbe\u8ba1\uff0c\u786e\u5b9e\u662f\u7b80\u5355\u3001\u76f4\u89c2\u7684\u5904\u7406\uff0c\u5728\u793e\u533a\u5f62\u6210\u4e86\u89d2\u529b\u3002<\/p>\n
try-handler \u63d0\u6848<\/h2>\n
\u672c\u6b21\u63d0\u6848\u4e2d\u6240\u63d0\u5230\u7684\u89e3\u51b3\u65b9\u6848\uff0c\u662f\u589e\u52a0\u4e00\u4e2a\u65b0\u8bed\u53e5 try \uff0c\u4ee5\u6b64\u8fbe\u5230\u7b80\u6d01\u7684\u9519\u8bef\u5904\u7406\u7684\u4f5c\u7528\uff0c\u8ba9 if err != nil \u7684\u5904\u7406\u4e1d\u6ed1\u8d77\u6765\u3002<\/p>\n
\u5982\u4e0b\u4ee3\u7801\uff1a<\/p>\n
try err, handler<\/code><\/pre>\n
\u7f16\u8bd1\u5668\u7ffb\u8bd1\u540e\u751f\u6210\u7684\u4ee3\u7801\uff1a<\/p>\n
if err != nil {\n    return handler(err)\n}<\/code><\/pre>\n
\u5728\u51fd\u6570\u4e2d\u53ef\u4ee5\u5982\u4e0b\uff1a<\/p>\n
func(args...) (rtype1, rtypes..., rtypeN, error) {\n    try err, handler\n    ...\n}<\/code><\/pre>\n
\u7ffb\u8bd1\u540e\u751f\u6210\u7684\u4ee3\u7801\uff1a<\/p>\n
func(args...) (rtype1, rtypes..., rtypeN, error) {\n    if err != nil {\n            return Zero(rtype1), Zeros(rtypes...)..., Zero(rtypeN), handler(err)\n    }\n    ...\n}<\/code><\/pre>\n
\u4e5f\u53ef\u4ee5\u53ea\u9488\u5bf9 if err != nil \u5904\u7406\u3002\u5982\u4e0b\u4ee3\u7801\uff1a<\/p>\n
try err<\/code><\/pre>\n
\u7ffb\u8bd1\u540e\u751f\u6210\u7684\u4ee3\u7801\uff1a<\/p>\n
if err != nil {\n    return err\n}<\/code><\/pre>\n
\u4e0d\u4f1a\u8c03\u7528\u4e0d\u5b58\u5728\u7684 handler \u8fdb\u884c\u5904\u7406\uff0c\u5c06\u4f1a\u76f4\u63a5\u8fd4\u56de\u3002\u4e09\u884c\uff08if err != nil \u7684\u903b\u8f91\uff09\u76f4\u63a5\u53d8 3 \u4e2a\u5355\u8bcd\uff08try\uff09\u3002<\/p>\n
\u4e0d\u60f3\u5199\u51fd\u6570\uff0c\u4e5f\u53ef\u4ee5\u76f4\u63a5\uff1a<\/p>\n
x, err := f()\ntry err, fmt.Errorf("f fail: %w", err)<\/code><\/pre>\n
\u9488\u5bf9 defer+try \u7684\u573a\u666f\u53ef\u4ee5\u5982\u4e0b\uff1a<\/p>\n
func CopyFile(src, dst string) error {\n    defer try func(err error) error {\n        return fmt.Errorf("copy %s %s: %w", src, dst, err)\n    }\n    ...\n}<\/code><\/pre>\n
\u5165\u53c2\u662f\u6bd4\u8f83\u7075\u6d3b\u7684\uff0c\u4f5c\u8005\u5e0c\u671b\u5b83\u662f\u6cdb\u578b\uff0c\u8fd9\u6837\u80fd\u591f\u9002\u914d\u5404\u79cd\u573a\u666f\u7684\u8981\u6c42\u3002<\/p>\n
\u793a\u4f8b\u548c\u5b9e\u8df5<\/h2>\n
\u9488\u5bf9\u672c\u63d0\u6848\uff0c\u539f\u4f5c\u8005\u7ed9\u51fa\u4e86\u5404\u7c7b\u4f7f\u7528\u573a\u666f\u7684\u793a\u4f8b\u3002\u5982\u4e0b\u4ee3\u7801\uff1a<\/p>\n
import (\n    "fmt"\n)\n\n\/\/ This helper should be defined in the fmt package\nfunc Handlew(format string, args ...any) func(error) error {\n    return func(err error) error {\n        args = append(args, err)\n        return fmt.Errorf(format+": %w", args...)\n    }\n}\n\n\/\/ This helper should be defined in the fmt package\nfunc Handlef(format string, args ...any) func(error) error {\n    return func(err error) error {\n        args = append(args, err)\n        return fmt.Errorf(format+": %v", args...)\n    }\n}\n\nfunc valAndError() (int, error) {\n    return 1, fmt.Errorf("make error")\n}\n\nfunc newGo() (int, error) {\n    x, err := valAndError()\n    try err\n\n    \/\/ Common formatting functions will already be provided\n    i := 2\n    x, err = valAndError()\n    try err, Handlew("custom Error %d", i)\n\n    \/\/ Using a custom error type\n    \/\/ For convenience the error type can expose a method to set the error\n    x, err = valAndError()\n    try err, TheErrorAsHandler(i)\n}\n\ntype TheError struct{\n    num int\n    err error\n}\n\nfunc (t TheError) Error() String {\n    return fmt.Sprintf("theError %d %v", t.num, t.err)\n}\n\nfunc TheErrorAsHandler(num int) func(err) TheError {\n    return func(err error) TheError {\n        return theError{ num: i, err: err }\n    }\n}<\/code><\/pre>\n
\u53e6\u5916\u5728\u65e5\u5e38\u7684 Go \u5de5\u7a0b\u4e2d\uff0c\u63d0\u6848\u4f5c\u8005\u8ba4\u4e3a CopyFile \u51fd\u6570\u662f\u65b0\u63d0\u6848\u8bed\u53e5\u7684\u4e00\u79cd\u5f88\u597d\u7684\u5b9e\u8df5\u3002\u4e3a\u6b64\u57fa\u4e8e try-handler \u8fdb\u884c\u4e86\u4e00\u7248\u6539\u9020\u548c\u8bf4\u660e\u3002<\/p>\n
\u5982\u4e0b\u4ee3\u7801\uff1a<\/p>\n
\/\/ This helper can be used with defer\nfunc handle(err *error, handler func(err error) error) {\n    if err == nil {\n        return nil\n    }\n    *err = handler(err)\n}\n\nfunc CopyFile(src, dst string) (err error) {\n    defer handle(&err, func(err error) error {\n        return fmt.Errorf("copy %s %s: %w", src, dst, err)\n    })\n\n    r, err := os.Open(src)\n    try err\n    defer r.Close()\n\n    w, err := os.Create(dst)\n    try err, func(err error) error {\n            os.Remove(dst) \/\/ only if Create fails\n            return fmt.Errorf("dir %s: %w", dst, err)\n    }\n    defer w.Close()\n\n    err = io.Copy(w, r)\n    try err\n    err = w.Close()\n    try err\n    return nil\n}<\/code><\/pre>\n
\u5f15\u5165 try-hanlder \u540e\uff0c\u80fd\u591f\u505a\u5230\uff1a<\/p>\n