前往:将引用类型作为参数

问题描述

Go中的某些类型是引用类型:映射，切片，通道，函数和方法.

Certain types in Go are reference types: maps, slices, channels, functions, and methods.

有时您需要使用指向引用的指针.例如，

Sometimes you need to use pointers to references. For example,

type Stack []interface{}
func (stack *Stack) Push(x interface{}) {
    *stack = append(*stack, x)
}

之所以需要它，是因为所有参数都是通过复制值来传递的，并且 append()可能需要在分片的容量不够大的情况下重新分配内存.我明白了.

You need it because all arguments are passed by copying the value, and append() might need to reallocate memory in the slice's capacity is not big enough. I get that.

第一个问题. map 类型如何?如果我有一个基于 map 的自定义类型，那么如果需要某些key:value插入或删除操作，我是否应该最好始终传递一个指向它的指针?

First question. How about map types? If I have a custom type based on a map, should I better always pass a pointer to it if some key:value insertions or deletions are expected?

第二个问题.其他参考类型呢?例如 Channel .我可以想象这样一种情况，我将基于通道构建自定义类型，以对传递到通道的值实施一些自定义预处理.这里也需要指针吗?

Second question. What about other reference types? Channel, for example. I can imagine a situation where I build a custom type based on a channel to implement some custom pre-processing for the values being passed to a channel. Pointers needed here too?

很抱歉，如果这是基本内容，但是我真的想很好地理解这个主题.

Sorry if this is basic as heck, but I really want to get a good grasp of the subject.

推荐答案

当您将所有内容都视为一个值(其中某些值内部包含指针)时，规则相当简单.

The rules are fairly easy when you think of everything as a value, where some values contain pointers internally.

• 切片:当您需要修改长度或容量以更改切片的值时，请使用指针.
• 地图:请勿使用指针，因为地图值不会随着修改而改变.
• 函数和方法:不要使用指针，通过函数值具有相同的效果.
• chan :请勿使用指针.

• slices: Use a pointer when you may need to modify the length or capacity, which changes the value of the slice.
• maps: Don't use a pointer, since the map value doesn't change with modifications.
• functions and methods: Don't use a pointer, the same effect is had through function values.
• chan: Don't use a pointer.

当然也有例外，例如，如果您希望能够完全交换出地图，则需要使用指针来进行交换，但这是极少数情况.

There are of course exceptions, like if you want to be able to swap out a map entirely you would need to use pointer to do so, but these are rare cases.

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