Let Handler() return an error instead of panicking. Also removed checks for / and * since they are checked in newPath().

httpr.go

@@ -157,22 +157,21 @@ func (rr *Router) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 // Handler registers a handler for provided pattern for a given HTTP method.
-func (rr *Router) Handler(method, pattern string, handler http.HandlerFunc) {
-	if pattern[0] != '/' {
-		panic("first element of path should be a slash (/) symbol")
-	}
-
-	if strings.Count(pattern, "*") > 1 {
-		panic("there can be only one wildcard (*) symbol in path")
+func (rr *Router) Handler(method, pattern string, handler http.HandlerFunc) error {
+	path, err := newPath(pattern)
+	if err != nil {
+		return err
 	}
 
 	if rr.tree[method] == nil {
 		rr.tree[method] = &node{endpoint: "/"}
 	}
 
-	path, _ := newPath(pattern)
+	if err := rr.tree[method].add(path, handler); err != nil {
+		return err
+	}
 
-	rr.tree[method].add(path, 0, handler)
+	return nil
 }
 
 // ServeStatic serves a given file system.