从类型断言的接口切片中删除元素 [英] Removing an element from a type asserted Slice of interfaces

问题描述

在Golang中，断言一个切片后，如何能够从该切片中删除元素?

In Golang, after asserting to a slice, how is one able to remove an element from said slice?

例如，以下内容返回错误无法分配给值.([[interface {} interface]}

For example, the following returns the error cannot assign to value.([]interface {})

value.([]interface{}) = append(value.([]interface{})[:i],value.([]interface{})[i+1:]...)

推荐答案

如果接口中包含切片值，则无法对其进行更改.您不能更改包装在接口中的任何值.

If you have a slice value wrapped in an interface, you can't change it. You can't change any value wrapped in interfaces.

创建接口值以包装值时，将创建一个副本并将其存储在接口中.

When an interface value is created to wrap a value, a copy is made and stored in the interface.

当您输入内容时，将获得该值的副本，但不能在界面中更改该值.这就是为什么不允许为其分配值的原因，就像您将被允许的那样，您只会为副本分配一个新值(作为类型断言的结果获取).但是存储在界面中的值将不会被更改.

When you type-assert it, you get a copy of the value, but you can't change the value in the interface. That's why it's not allowed to assign a value to it, as if it would be allowed, you would only assign a new value to a copy (that you acquire as the result of the type assertion). But the value stored in the interface would not be changed.

如果这确实是您想要的东西，则必须将切片指针存储在接口中，例如 * [] interface {} .这不会改变您无法更改接口中值的事实，但是由于这一次它是一个指针，因此我们不想更改指针，而是要更改 pointed 值(即切片值).

If this is indeed something you want, then you must store a slice pointer in the interface, e.g. *[]interface{}. This doesn't change the fact that you can't change the value in the interface, but since this time it's a pointer, we don't want to change the pointer but the pointed value (which is the slice value).

请参见此示例演示其工作原理:

See this example demonstrating how it works:

s := []interface{}{0, "one", "two", 3, 4}

var value interface{} = &s

// Now do the removal:
sp := value.(*[]interface{})

i := 2
*sp = append((*sp)[:i], (*sp)[i+1:]...)

fmt.Println(value)

输出(在游乐场上尝试):

&[0 one 3 4]

如您所见，我们删除了索引 2 上的元素，该元素为"two" ，现在在打印接口值时从结果中删除了该元素.

As you can see, we removed the element at index 2 which was "two" which is now "gone" from the result when printing the interface value.

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