具有多种返回类型的接口方法 [英] Interface method with multiple return types

问题描述

我正在为接口苦苦挣扎.考虑一下:

I'm struggling with interfaces. Consider this:

type Generatorer interface {
    getValue() // which type should I put here ? 
}

type StringGenerator struct {
    length         int
}

type IntGenerator struct {
    min            int
    max            int
}

func (g StringGenerator) getValue() string {
    return "randomString"
}

func (g IntGenerator) getValue() int {
    return 1
}

我希望getValue()函数返回 string 或 int ，具体取决于是从StringGenerator还是IntGenerator

I want the getValue() function to return a string or an int, depending on if it's called from StringGenerator or IntGenerator

当我尝试对此进行编译时，出现以下错误:

When I try to compile this, I get following error:

不能将s(* StringGenerator类型)用作数组中的类型Generator或 切片文字: * StringGenerator未实现Generatorer(getValue方法的类型错误)

cannot use s (type *StringGenerator) as type Generatorer in array or slice literal: *StringGenerator does not implement Generatorer (wrong type for getValue method)

具有getValue()字符串
想要getValue()

have getValue() string
want getValue()

我该如何实现?

推荐答案

您可以以这种方式实现:

type Generatorer interface {
    getValue() interface{}
}

type StringGenerator struct {
    length         int
}

type IntGenerator struct {
    min            int
    max            int
}

func (g StringGenerator) getValue() interface{} {
    return "randomString"
}

func (g IntGenerator) getValue() interface{} {
    return 1
}

空接口允许所有值.这允许使用通用代码，但基本上使您无法使用功能非常强大的Go类型系统.

The empty interface allows every value. This allows for generic code but basically stops you from using the very powerful type system of Go.

在您的示例中，如果使用getValue函数，您将获得类型为interface{}的变量，如果要使用它，则需要知道它实际上是字符串还是整数:您将需要很多reflect使您的代码变慢.

In your example if you use the getValue function, you will get a variable of type interface{} and if you want to work with it, you need to know if it actually is a string or an int: you will need a lot of reflect making your code slow.

来自Python，我习惯于编写非常通用的代码.学习Go时，我不得不停止这种想法.

Coming from Python I was used to code very generic. When learning Go I had to stop thinking that way.

在您的特定情况下，这不能代表我的意思，因为我不知道StringGenerator和IntGenerator的用途.

What that means in your specific case I can't say because I don't know what StringGenerator and IntGenerator are being used for.

这篇关于具有多种返回类型的接口方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！