检查value是否实现接口的说明 [英] Explanation of checking if value implements interface

问题描述

我读过Effective Go和其他Q&如下： golang接口合规性编译类型检查，但是我无法正确理解如何使用这种技术。

I've read "Effective Go" and other Q&As like this: golang interface compliance compile type check , but nonetheless I can't understand properly how to use this technique.

请参阅示例：

type Somether interface {
    Method() bool
}

type MyType string

func (mt MyType) Method2() bool {
    return true
}

func main() {
    val := MyType("hello")

    //here I want to get bool if my value implements Somether
    _, ok := val.(Somether)
    //but val must be interface, hm..what if I want explicit type?

    //yes, here is another method:
    var _ Iface = (*MyType)(nil)
    //but it throws compile error
    //it would be great if someone explain the notation above, looks weird
}

有没有简单的方法（例如，不使用反射）检查值是否实现了接口？

Is there any simple ways (eg without using reflection) check value if it implements an interface?

推荐答案

您只需检查一个值是否实现了如果你不知道值的类型接口。
如果类型已知，则该检查由编译器自动完成。

You only have to check if a value implements an interface if you don't know the value's type. If the type is known, that check is automatically done by the compiler.

如果你真的想要检查，你可以使用第二种方法你给了：

If you really want to check anyways, you can do it with the second method you gave:

var _ Somether = (*MyType)(nil)

在编译时会出错：

prog.go:23: cannot use (*MyType)(nil) (type *MyType) as type Somether in assignment:
    *MyType does not implement Somether (missing Method method)
 [process exited with non-zero status]

你在这里做的是分配 MyType <的指针/ code>键入（并且 nil value）到类型 Somether 的变量，但是因为变量名称是 _ 它被忽略。

What you are doing here, is assigning a pointer of MyType type (and nil value) to a variable of type Somether, but since the variable name is _ it is disregarded.

如果 MyType 已实施 Somether ，它会编译并且什么都不做

If MyType implemented Somether, it would compile and do nothing

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