英文:
Slice storage reference in Go
问题
在Go库源代码中，经常可以看到通过创建一个新的切片存储引用来传递切片，例如：
method(s[:])
与直接传递原始切片相比，这样做有什么好处呢？
method(s)
英文:
In the Go library source you often see that a slice is passed by creating a new slice storage reference like so
method(s[:])
What's the benefit of this, compared to just passing the original slice?
method(s)
答案1
得分: 6
s[:]构造通常只用于创建一个引用现有数组的新切片，而不是用于“传递原始切片”。
如果在stdlib中确实使用了s[:]，并且s是一个切片，那么它可能是一个重构遗留下来的。如果您知道这样的地方，请在Go的问题跟踪器上报告。
英文:
The s[:] construct is normally used only to create a new slice referencing an existing array, not for "passing the original slice".
If s[:] is really used somewhere in the stdlib and s is a slice than it could be e.g. a refactoring leftover. Please report such place if known to you on the Go issue tracker.
答案2
得分: 1
你只会在s是一个数组的情况下看到这样的代码，而且你想将其作为参数传递给一个以切片作为输入的函数。看下面的代码。
package main
func main() {
x := [...]int{1, 2, 3, 4, 5}
someFunction(x) // 类型不匹配错误：期望 [] int，传递了 [5] int
someFunction(x[:])// 没有错误
}
func someFunction(input []int){
// 使用 input
}
需要注意的是，[] int 和 [5] int 是完全不同的类型。
英文:
The only case where you would see code like this is when s is an array, and you want to pass as a parameter to a function that takes a slice as its input. Take the following code.
package main
func main() {
x := [...]int{1, 2, 3, 4, 5}
someFunction(x) // type mismatch error : expecting [] int, passed [5] int
someFunction(x[:])// no error
}
func someFunction(input []int){
// use input
}
The thing to note here is that [] int and [5] int are entirely different types.
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