function - 如何使用函数作为 map 的键

Question

如何使用函数作为 map 的键？例如:

type Action func(int)
func test(a int) { }
func test2(a int) { }

func main() {
  x := map[Action]bool{}
  x[test] = true
  x[test2] = false
}

这些代码会显示错误:invalid map key type Action

Answer 1

您不能将函数用作映射键。 language specification明确地说:

The comparison operators == and != must be fully defined for operands of the key type; thus the key type must not be a function, map, or slice.