Difference between http.Handle and http.HandleFunc?

Question

The Go docs have the following example for the http package:

http.Handle("/foo", fooHandler) http.HandleFunc("/bar", func(w http.ResponseWriter, r *http.Request) {     fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path)) }) 

I'm having sort of a difficulty understanding the difference between Handle and HandleFunc and why two are needed. Can somebody try to explain to a new Gopher in clear words?

Answer 1

Basically, the HTTP server's "mux" has a map of path -> handler interface

Interfaces are used here, I assume, to allow you to implement complex path handlers that have state.

For example the file server from the standard package is a struct that contains the root dir for file service and implements the handler interface.

That said, for simple stuff, a func is easier and more clear. So they added a special generator so you can easily pass in a func.

Take a look at: server.go

from line: 1216 (as of today)

  1216  type HandlerFunc func(ResponseWriter, *Request)   1217     1218  // ServeHTTP calls f(w, r).   1219  func (f HandlerFunc) ServeHTTP(w ResponseWriter, r *Request) {   1220      f(w, r)   1221  } 

What they are doing is implementing the interface on a custom type (which happens to match the api of the interface) that just calls itself.