http.Handle(Handler 或 HandlerFunc)

Question

下面的功能是如何实现的？

func handle(pattern string, handler interface{}) {
    // ... what goes here? ...
    http.Handle(pattern, ?)
}

handle("/foo", func(w http.ResponseWriter, r http.Request) { io.WriteString(w, "foo") }
handle("/bar", BarHandler{})

handle() 被传递给匹配 http.HandlerFunc 类型的函数或实现 http.Handler 接口(interface)的类型。

Answer 1

与其诉诸反射(reflection)，我会这样做:

func handle(pattern string, handler interface{}) {
    var h http.Handler
    switch handler := handler.(type) {
    case http.Handler:
        h = handler
    case func(http.ResponseWriter, *http.Request):
        h = http.HandlerFunc(handler)
    default:
        // error
    }
    http.Handle(pattern, h)
}