18.5 接口

    （2）如何使用接口实现一个类型分类函数：

    1. func classifier(items ...interface{}) {
    2.     for i, x := range items {
    3.         switch x.(type) {
    4.         case bool:
    6.             fmt.Printf("param #%d is a float64\n", i)
    7.         case int, int64:
    8.             fmt.Printf("param #%d is an int\n", i)
    9.         case nil:
    11.         case string:
    12.         default:
    13.             fmt.Printf("param #%d’s type is unknown\n", i)
    14.         }
    16. }