errors _ golang-优快云博客

本文介绍了Go语言中处理错误的独特方式，通过使用明确的返回值来传递错误信息，并对比了与其他语言如Java和Ruby中异常处理的不同。通过示例展示了如何自定义错误类型。

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In Go it's idiomatic to communicate errors via an explicit, separate return value. this constrasts errors via an explicit, separate return value. This constrasts with the exceptions used in languages like Java and Ruby and the overloaded single result / error value sometimes used in C. Go's approach makes it easy to see which functions return errors and to handle them using the same language constructs employed for any other, non-error tasks

package main

import (
    "errors"
    "fmt"
)

func f1(arg int) (int, error) {
    if arg == 42 {
        return -1, errors.New("can't work with 42")
    }
    return arg + 3, nil
}

type argError struct {
    arg  int
    prob string
}

func (e *argError) Error() string {
    return fmt.Sprintf("%d - %s", e.arg, e.prob)
}

func f2(arg int) (int, error) {
    if arg == 42 {
        return -1, &argError{arg, "can't work with it"}
    }

    return arg + 3, nil
}

func main() {

    for _, i := range []int{7, 42} {
        if r, e := f1(i); e != nil {
            fmt.Println("f1 failed : ", e)
        } else {
            fmt.Println("f2 worked : ", r)
        }
    }

    for _, i := range []int{7, 42} {
        if r, e := f2(i); e != nil {
            fmt.Println("f2 failed : ", e)
        } else {
            fmt.Println("f2 worked : ", r)
        }
    }

    _, e := f2(42)
    if ae, ok := e.(*argError); ok {
        fmt.Println(ae.arg)
        fmt.Println(ae.prob)
    }
}

f2 worked :  10
f1 failed :  can't work with 42
f2 worked :  10
f2 failed :  42 - can't work with it
42
can't work with it

总结 :

　　1 : golang 的内建函数 builtin.go 里面定义了 type error interface{ Error() string }; 实现了这个方法就是自定义的 Error(查看源码 command + shift + 鼠标左键)

　　2 : ....

转载于:https://www.cnblogs.com/jackkiexu/p/4338023.html