Chaining http handlers

chain.go

package chain

import (
	"net/http"
)

type Chain handlerFunc
type handlerFunc func(http.ResponseWriter, *http.Request)

func NewChain(handlers ...handlerFunc) Chain {
	if handlers == nil || len(handlers) == 0 {
		panic("no handlers were passed")
	}
	var c Chain
	for _, h := range handlers {
		if h == nil {
			panic("nil handler")
		}
		c = c.add(h)
	}
	return c
}

func (c Chain) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	c(w, r)
}

func (c Chain) add(f handlerFunc) Chain {
	return func(w http.ResponseWriter, r *http.Request) {
		if c != nil {
			c(w, r)
		}
		f(w, r)
	}
}