Golang 函数内的嵌套类 [英] Golang nested class inside function

问题描述

Go 支持在函数内部嵌套结构体，但除了 lambda 不支持嵌套函数，是否意味着无法在函数内部定义嵌套类?

Go supports nested struct inside function but no nested function except lambda, does it mean there is no way to define a nested class inside function?

func f() {
    // nested struct Cls inside f
    type Cls struct {
    ...
    }
    // try bounding foo to Cls but fail
    func (c *Cls) foo() {
    ...
    }
}

因此感觉有点奇怪，类在函数内部被削弱了.

Thus it feels a bit strange that class is weaken inside function.

有什么提示吗?

推荐答案

实际上，声明函数with 还是without 接收器并不重要:不允许在 Go 中使用嵌套函数.

Actually it doesn't matter if you want to declare the function with or without a receiver: nesting functions in Go are not allowed.

虽然你可以使用函数字面量来实现这样的效果:

Although you can use Function literals to achieve something like this:

func f() {
    foo := func(s string) {
        fmt.Println(s)
    }

    foo("Hello World!")
}

这里我们创建了一个变量foo，它有一个函数类型，它被定义在另一个函数f中.调用外部"函数 f 输出:"Hello World!" 正如预期的那样.

Here we created a variable foo which has a function type and it is delcared inside another function f. Calling the "outer" function f outputs: "Hello World!" as expected.

在 Go Playground 上试试.

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