use direct result of switch type assertion

web/middleware.go

@@ -52,14 +52,13 @@ func (s *cStack) ServeHTTPC(c C, w http.ResponseWriter, r *http.Request) {
 
 func (m *mStack) appendLayer(fn interface{}) {
 	ml := mLayer{orig: fn}
-	switch fn.(type) {
+	switch f := fn.(type) {
 	case func(http.Handler) http.Handler:
-		unwrapped := fn.(func(http.Handler) http.Handler)
 		ml.fn = func(c *C, h http.Handler) http.Handler {
-			return unwrapped(h)
+			return f(h)
 		}
 	case func(*C, http.Handler) http.Handler:
-		ml.fn = fn.(func(*C, http.Handler) http.Handler)
+		ml.fn = f
 	default:
 		log.Fatalf(`Unknown middleware type %v. Expected a function `+
 			`with signature "func(http.Handler) http.Handler" or `+

web/pattern.go

@@ -32,13 +32,13 @@ type Pattern interface {
 }
 
 func parsePattern(p interface{}) Pattern {
-	switch p.(type) {
+	switch v := p.(type) {
 	case Pattern:
-		return p.(Pattern)
+		return v
 	case *regexp.Regexp:
-		return parseRegexpPattern(p.(*regexp.Regexp))
+		return parseRegexpPattern(v)
 	case string:
-		return parseStringPattern(p.(string))
+		return parseStringPattern(v)
 	default:
 		log.Fatalf("Unknown pattern type %v. Expected a web.Pattern, "+
 			"regexp.Regexp, or a string.", p)

web/router.go

@@ -69,16 +69,14 @@ func (h netHTTPWrap) ServeHTTPC(c C, w http.ResponseWriter, r *http.Request) {
 }
 
 func parseHandler(h interface{}) Handler {
-	switch h.(type) {
+	switch f := h.(type) {
 	case Handler:
-		return h.(Handler)
+		return f
 	case http.Handler:
-		return netHTTPWrap{h.(http.Handler)}
+		return netHTTPWrap{f}
 	case func(c C, w http.ResponseWriter, r *http.Request):
-		f := h.(func(c C, w http.ResponseWriter, r *http.Request))
 		return HandlerFunc(f)
 	case func(w http.ResponseWriter, r *http.Request):
-		f := h.(func(w http.ResponseWriter, r *http.Request))
 		return netHTTPWrap{http.HandlerFunc(f)}
 	default:
 		log.Fatalf("Unknown handler type %v. Expected a web.Handler, "+