Go decorators - Logging for HTTP Requests

// gist saved for future use
// practice code of the decorator pattern for http requests
// extracted from the talk of Tomas Senart (http://bit.ly/22tUcl4)
package main

import (
	"log"
	"net/http"
	"os"
)

type Client interface {
	Do(*http.Request) (*http.Response, error)
}

// ClientFunc is a function type that implements the Client interface.
type ClientFunc func(*http.Request) (*http.Response, error)

func (f ClientFunc) Do(r *http.Request) (*http.Response, error) {
	return f(r)
}

// A Decorator wraps a Client with extra behaviour
type Decorator func(c Client) Client

// Logging returns a Decorator that logs a Client's requests
func Logging(l *log.Logger) Decorator {
	return func(c Client) Client {
		return ClientFunc(func(r *http.Request) (*http.Response, error) {
			l.Printf("%s: %s %s", r.UserAgent, r.Method, r.URL)
			return c.Do(r)
		})
		
	}
}

// Decorate decorates a Client c with all the given Decorators, in order.
func Decorate(c Client, ds ...Decorator) Client {
	decorated := c
	for _, decorate := range ds {
		decorated = decorate(decorated)
	}
	return decorated
}

func main() {
	cli := Decorate(http.DefaultClient,
			Logging(log.New(os.Stdout, "client: ", log.LstdFlags)),
	)
	
	req, err := http.NewRequest("GET", "www.google.com", nil)
	if err != nil {
		panic(err)
	}
	cli.Do(req)
}