有没有可能为命名类型/结构定义相等性？ [英] Is it possible to define equality for named types/structs?

问题描述

阅读相关问题，关于在地图中使用切片后，我成了对Go的平等很好奇。

After reading a related question about using slices in maps, I became curious about equality in Go.

我知道可以覆盖Java <$ c $的等于方法C>对象。是否有类似的方式来定义Go如何检查用户定义的类型/结构是否相等？如果是这样，那么对于上面引用的问题将有一个解决方法。我想过使用 界面{} 值可能会提供一个解决方案，但我收到了错误消息 panic：运行时错误：不可用类型的哈希[] int 。

I know it's possible to override the equals method of a Java Object. Is there a similar way to define how Go checks user defined types/structs for equality? If so, there would be a workaround for the issue referenced above. I thought using interface{} values might offer a solution but I received the error message panic: runtime error: hash of unhashable type []int.

推荐答案

Go支持相等检查结构。

Go supports equality checking structs.

type Person struct {
    Name string
}

a := Person{"Bill DeRose"}
b := Person{"Bill DeRose"}

a == b // true

因为指针地址是不同的，所以它不会与指针字段一起工作（以您想要的方式）。

It won't work with pointer fields (in the way you want) because the pointer addresses are different.

type Person struct {
    Friend *Person
}

a := Person{Friend: &Person{}}
b := Person{Friend: &Person{}}

a == b // false

您无法修改相等运算符，也没有内置方法来添加对自定义类型的支持以使用 = = 语法。相反，您应该使用 reflect.DeepEqual 来比较指针值。 。

You can't modify the equality operator and there is no built-in way to add support for custom types to use == syntax. Instead you should compare the pointer values using reflect.DeepEqual.

import "reflect"

a := Person{Friend: &Person{}}
b := Person{Friend: &Person{}}

reflect.DeepEqual(a, b) // true

记住有些警告。

Keep in mind there are caveats.

一般来说，DeepEqual是Go的==运算符的递归放松。然而，这个想法是不可能实现的，没有一些不一致。具体而言，一个值可能与自身不相等，或者是因为它是func类型（通常无法比较），或者因为它是浮点型NaN值（在浮点比较中不等于自身），或者因为它是浮点型它是包含这样一个值的数组，结构或接口。

In general DeepEqual is a recursive relaxation of Go's == operator. However, this idea is impossible to implement without some inconsistency. Specifically, it is possible for a value to be unequal to itself, either because it is of func type (uncomparable in general) or because it is a floating-point NaN value (not equal to itself in floating-point comparison), or because it is an array, struct, or interface containing such a value.

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