Golang中的函数声明 [英] Function declaration in Golang

问题描述

似乎有两种不同的方法可以在Golang中声明一个函数，如下所示:

It seems there are two different ways to declare a function in Golang, like this:

package main
import "fmt"
var someFunc = func(arg string) {
    fmt.Println(arg)
}
func main() {
    someFunc("Hello")
}

上面的作品.但是，以下方法不起作用:

The above works. However, the below does not work:

package main
import "fmt"
var someFunc = func(arg string) {
    fmt.Println(arg)
}
var main = func() {
    someFunc("Hello")
}

它将抱怨:

runtime.main: undefined: main.main

那么 func someFunc()和 var someFunc = func()之间有什么区别?

So what's the difference between func someFunc() and var someFunc = func()?

我发现它的原因可能也是因为我也编写了许多Javascript.在Go语言中，似乎很少有人看到像 var someFunc = func()这样的函数.在这两个中，我们可以说哪个比另一个更正确吗?

The reason I found this is probably because of I code a lot of Javascript, too. It seems in Go, I rarely see people declaring a function like var someFunc=func(). Of these two, can we say which one is more correct than the other one?

推荐答案

执行时

var someFunc = func(arg string) {}

您正在为 somefunc 变量分配一个匿名函数.您也可以这样写:

you are assigning an anonymous function to the somefunc variable. You could also write it like this:

somefunc := func(arg string) {}

创建函数的另一种方法是创建命名函数:

The other way to create a function is to create a named function:

func somefunc(arg string) {}

命名函数只能在顶层声明，而匿名函数可以在任何地方声明.而且 main 具有特殊的含义，在 main 包中必须有一个名为 main 的命名函数，这就是为什么您在第二种情况.

Named functions can only be declared at the top level whereas anonymous functions can be declared anywhere. And main has a special meaning, there has to be a named function called main in the main package, that's why you got an error in the second case.

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