Closure of Golang Learning

This is a creation in Article, where the information may have evolved or changed.

An anonymous function cannot exist independently, but can be assigned to a variable, that is, to hold the address of the function into the variable: and fplus := func(x, y int) int { return x + y } then invoke the function through the variable name:fplus(3,4)。

Of course, the anonymous function can also be called directly: func(x, y int) int { return x + y } (3, 4) .

func () {    = 0.0 for     i: = 1; I <= 1e6; i++ {        + = I    }} ()

The first pair of parentheses that represent the argument list must be next to the keyword func , because the anonymous function has no name. The curly braces {} cover the function body, and the last pair of parentheses indicate a call to the anonymous function.

Use defer to modify method return values in conjunction with anonymous functions (closures):

"FMT"int, str string) {    defer func () {        ret+ +    } ()    defer func () {        + = ("##########")    } (    )return , "111"}func Main () {    fmt. Println (f ())    }

Print output:

23 111 ##########

Closure instances:

 package mainimport  "FMT" func Main () {  var  F = Adder () fmt. Print (f ( 1), "-" ) fmt. Print (f (), "-" ) fmt. Print (f ( 300))}func Adder () func ( int ) int   { var  x int  return  func (Delta int ) int   {x  += Delta  return   X}}  

The first call to the Adder function returns a func (int) int function, and the value of the local variable x is incremented when re-tuned, and the final output is:

1  + 321