英文:
golang prepend a string to a slice ...interface{}
问题
我有一个方法，它的参数是 v ...interface{}，我需要在这个切片前面添加一个 string。以下是这个方法的代码：
func (l Log) Error(v ...interface{}) {l.Out.Println(append([]string{" ERROR "}, v...))}
当我尝试使用 append() 时，它不起作用：
> append("some string", v)append 的第一个参数必须是切片；有未命名的字符串类型> append([]string{"some string"}, v)无法将类型 []interface {} 用作 append 中的字符串类型
在这种情况下，正确的方法是什么？
英文:
I've a method that has as an argument v ...interface{}, I need to prepend this slice with a string. Here is the method:
func (l Log) Error(v ...interface{}) {l.Out.Println(append([]string{" ERROR "}, v...))}
When I try with append() it doesn't work:
> append("some string", v)first argument to append must be slice; have untyped string> append([]string{"some string"}, v)cannot use v (type []interface {}) as type string in append
What's the proper way to prepend in this case?
答案1
得分: 44
append() 只能追加与切片元素类型匹配的值：
func append(slice []Type, elems ...Type) []Type
因此，如果你的元素是 []interface{} 类型，你需要将初始的 string 包装在 []interface{} 中才能使用 append()：
s := "first"rest := []interface{}{"second", 3}all := append([]interface{}{s}, rest...)fmt.Println(all)
输出结果（在 Go Playground 上尝试）：
[first second 3]
英文:
append() can only append values of the type matching the element type of the slice:
func append(slice []Type, elems ...Type) []Type
So if you have the elements as []interface{}, you have to wrap your initial string in a []interface{} to be able to use append():
s := "first"rest := []interface{}{"second", 3}all := append([]interface{}{s}, rest...)fmt.Println(all)
Output (try it on the Go Playground):
[first second 3]
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