Go Language Basics - Error Handling

learning target

Master error handling

Master custom error handling

Mastering defer keyword

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Error Handling

GO no exception handling mechanism

Go language introduces a standard mode on error handling, error i.e. the interface, the interface is defined as follows:
type interface error {

​ Error() string

}

You can create instances rapid error by errors.New

errors.New("错误信息")

func Foo(param int)(n int, err error) {     
    // ...  
} 

//调用时的代码建议按如下方式处理错误情况： 
n, err := Foo(0)  
 
if err != nil {    
    // 错误处理 
} else {    
    // 使用返回值n  
} 

Custom error type

defer keyword

func CopyFile(dst, src string) (w int64, err error) {     
    srcFile, err := os.Open(src)     
    if err != nil {         
        return     
    } 
 
    defer srcFile.Close() 
 
    dstFile, err := os.Create(dstName)     
    if err != nil {         
        return     
    } 
 
    defer dstFile.Close() 
 
    return io.Copy(dstFile, srcFile)  
} 

Similar to Java's finally in

There may be a plurality of function defer statement

Call to defer statement is in compliance with last-out principle, that the latter statement will defer the first to be executed.

painc与recover

Error recovery may not be used for panic

Before panic exit will defer the implementation of the specified content

Error Recovery

defer func() {
    if err :=recover();err != nil { 
    //恢复错误
    }
}()

os.Exit exit

os.Exit terminate the program does not directly call the function specified defer

Output current information does not call stack when os.Exit exit

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