Revert "Remove web.HandlerFunc"

This reverts commit aee21eb0bd.

Fixes #119.

web/router_test.go

@@ -88,7 +88,8 @@ var testHandlerTable = map[string]string{
 	"/a": "http fn",
 	"/b": "http handler",
 	"/c": "web fn",
-	"/d": "httpc",
+	"/d": "web handler",
+	"/e": "httpc",
 }
 
 func TestHandlerTypes(t *testing.T) {
@@ -105,7 +106,10 @@ func TestHandlerTypes(t *testing.T) {
 	m.Get("/c", func(c C, w http.ResponseWriter, r *http.Request) {
 		ch <- "web fn"
 	})
-	m.Get("/d", testHandler(ch))
+	m.Get("/d", HandlerFunc(func(c C, w http.ResponseWriter, r *http.Request) {
+		ch <- "web handler"
+	}))
+	m.Get("/e", testHandler(ch))
 
 	for route, response := range testHandlerTable {
 		r, _ := http.NewRequest("GET", route, nil)

web/web.go

@@ -38,6 +38,22 @@ type Handler interface {
 	ServeHTTPC(C, http.ResponseWriter, *http.Request)
 }
 
+// HandlerFunc is similar to net/http's http.HandlerFunc, but supports a context
+// object. Implements both http.Handler and Handler.
+type HandlerFunc func(C, http.ResponseWriter, *http.Request)
+
+// ServeHTTP implements http.Handler, allowing HandlerFunc's to be used with
+// net/http and other compliant routers. When used in this way, the underlying
+// function will be passed an empty context.
+func (h HandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	h(C{}, w, r)
+}
+
+// ServeHTTPC implements Handler.
+func (h HandlerFunc) ServeHTTPC(c C, w http.ResponseWriter, r *http.Request) {
+	h(c, w, r)
+}
+
 /*
 PatternType is the type denoting Patterns and types that Goji internally
 converts to Pattern (via the ParsePattern function). In order to provide an