将结构指针转换为 Golang 中的接口指针 [英] Cast a struct pointer to interface pointer in Golang

问题描述

我有一个功能

func doStuff(inout *interface{}) {...}

此函数的目的是能够将任何类型的指针视为输入.但是当我想用结构的指针调用它时，我有一个错误.

type MyStruct struct {f1 整数}

当调用doStuff

ms := MyStruct{1}doStuff(&ms)

我有

test.go:38: 不能在 doStuff 的参数中使用 &ms (type *MyStruct) 作为类型 **interface {}

如何将 &ms 转换为与 *interface{} 兼容?

解决方案

没有指向接口的指针"这样的东西；(从技术上讲，您可以使用一个，但通常您不需要它).

如:

ms := MyStruct{1}doStuff(&ms)fmt.Printf(你好，操场:%v
", ms)

输出:

你好，游乐场:{1}

---

由于 newacct 提到了 在评论中:

<块引用>

直接将指针传递给接口是有效的，因为如果 MyStruct 符合协议，那么 *MyStruct 也符合协议(因为类型的方法集包含在其指针类型的方法集).

在这种情况下，接口是空接口，因此它无论如何都接受所有类型，但仍然如此.

I have a function

func doStuff(inout *interface{}) {
   ...
}

the purpose of this function is to be able to treat a pointer of any type as input. But when I want to call it with a the pointer of a struct I have an error.

type MyStruct struct {
    f1 int
}

When calling doStuff

ms := MyStruct{1}
doStuff(&ms)

I have

test.go:38: cannot use &ms (type *MyStruct) as type **interface {} in argument to doStuff

How can I cast &ms to be compatible with *interface{}?

解决方案

There is no such thing as a "pointer to an interface" (technically, you can use one, but generally you don't need it).

As seen in "what is the meaning of interface{} in golang?", interface is a container with two words of data:

• one word is used to point to a method table for the value’s underlying type,
• and the other word is used to point to the actual data being held by that value.

So remove the pointer, and doStuff will work just fine: the interface data will be &ms, your pointer:

func doStuff(inout interface{}) {
   ...
}

See this example:

ms := MyStruct{1}
doStuff(&ms)
fmt.Printf("Hello, playground: %v
", ms)

Output:

Hello, playground: {1}

---

As newacct mentions in the comments:

Passing the pointer to the interface directly works because if MyStruct conforms to a protocol, then *MyStruct also conforms to the protocol (since a type's method set is included in its pointer type's method set).

In this case, the interface is the empty interface, so it accepts all types anyway, but still.

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