diff --git a/http-ws/src/codec.rs b/http-ws/src/codec.rs
index d81c45a4..dc52f8d3 100644
--- a/http-ws/src/codec.rs
+++ b/http-ws/src/codec.rs
@@ -67,6 +67,12 @@ impl Flags {
     }
 }
 
+impl Default for Codec {
+    fn default() -> Self {
+        unimplemented!("please use Codec::new")
+    }
+}
+
 impl Codec {
     /// Create new WebSocket frames decoder.
     pub const fn new() -> Codec {
diff --git a/http/src/builder.rs b/http/src/builder.rs
index a3c58925..de1f9b4f 100644
--- a/http/src/builder.rs
+++ b/http/src/builder.rs
@@ -40,6 +40,20 @@ pub struct HttpServiceBuilder<
     pub(crate) _body: PhantomData<fn(V, St)>,
 }
 
+impl Default
+    for HttpServiceBuilder<
+        marker::Http,
+        net::Stream,
+        tls::NoOpTlsAcceptorBuilder,
+        DEFAULT_HEADER_LIMIT,
+        DEFAULT_READ_BUF_LIMIT,
+        DEFAULT_WRITE_BUF_LIMIT,
+    >
+{
+    fn default() -> Self {
+        unimplemented!("please use HttpServiceBuilder::new")
+    }
+}
 impl
     HttpServiceBuilder<
         marker::Http,
diff --git a/http/src/util/middleware/context.rs b/http/src/util/middleware/context.rs
index 8058d438..0476fe85 100644
--- a/http/src/util/middleware/context.rs
+++ b/http/src/util/middleware/context.rs
@@ -186,7 +186,7 @@ mod router_impl {
             where
                 I: PathGen,
             {
-                fn path_gen(&mut self, prefix: String) -> String {
+                fn path_gen(&mut self, prefix: &str) -> String {
                     self.0.path_gen(prefix)
                 }
             }
diff --git a/http/src/util/service/router.rs b/http/src/util/service/router.rs
index 04126044..76e8c670 100644
--- a/http/src/util/service/router.rs
+++ b/http/src/util/service/router.rs
@@ -54,7 +54,7 @@ impl<Obj> Router<Obj> {
         F::Response: Service<Req>,
         Req: IntoObject<F::Route<F>, Arg, Object = Obj>,
     {
-        let path = builder.path_gen(String::from(path));
+        let path = builder.path_gen(path);
         assert!(self
             .routes
             .insert(path, Req::into_object(F::route_gen(builder)))
@@ -141,8 +141,8 @@ pub trait PathGen {
     /// path generator.
     ///
     /// default to passthrough of original prefix path.
-    fn path_gen(&mut self, prefix: String) -> String {
-        prefix
+    fn path_gen(&mut self, prefix: &str) -> String {
+        String::from(prefix)
     }
 }
 
@@ -162,7 +162,8 @@ impl<Obj> PathGen for Router<Obj>
 where
     Obj: PathGen,
 {
-    fn path_gen(&mut self, mut path: String) -> String {
+    fn path_gen(&mut self, path: &str) -> String {
+        let mut path = String::from(path);
         if path.ends_with("/*") {
             path.pop();
         }
@@ -171,12 +172,11 @@ where
             path.pop();
         }
 
-        if let Some(prefix) = self.prefix.replace(path.len()) {
-            self.prefix = Some(path.len() + prefix);
-        }
+        let prefix = self.prefix.get_or_insert(0);
+        *prefix += path.len();
 
         self.routes.iter_mut().for_each(|(_, v)| {
-            v.path_gen(path.clone());
+            v.path_gen(path.as_str());
         });
 
         path.push_str("/*");
@@ -230,7 +230,7 @@ impl<F, S, M> PathGen for PipelineT<F, S, M>
 where
     F: PathGen,
 {
-    fn path_gen(&mut self, prefix: String) -> String {
+    fn path_gen(&mut self, prefix: &str) -> String {
         self.first.path_gen(prefix)
     }
 }
@@ -253,7 +253,7 @@ impl<S> PathGen for RouterMapErr<S>
 where
     S: PathGen,
 {
-    fn path_gen(&mut self, prefix: String) -> String {
+    fn path_gen(&mut self, prefix: &str) -> String {
         self.0.path_gen(prefix)
     }
 }
@@ -324,7 +324,7 @@ mod object {
     pub struct RouteObject<Arg, S, E>(pub Box<dyn RouteService<Arg, Response = S, Error = E> + Send + Sync>);
 
     impl<Arg, S, E> PathGen for RouteObject<Arg, S, E> {
-        fn path_gen(&mut self, prefix: String) -> String {
+        fn path_gen(&mut self, prefix: &str) -> String {
             self.0.path_gen(prefix)
         }
     }
@@ -362,7 +362,7 @@ where
         where
             T: PathGen,
         {
-            fn path_gen(&mut self, prefix: String) -> String {
+            fn path_gen(&mut self, prefix: &str) -> String {
                 self.0.path_gen(prefix)
             }
         }
diff --git a/router/src/router.rs b/router/src/router.rs
index 0b222fac..331b22fb 100644
--- a/router/src/router.rs
+++ b/router/src/router.rs
@@ -9,6 +9,12 @@ pub struct Router<T> {
     root: Node<T>,
 }
 
+impl<T> Default for Router<T> {
+    fn default() -> Self {
+        unimplemented!("please use Router::new");
+    }
+}
+
 impl<T> Router<T> {
     /// Construct a new router.
     pub const fn new() -> Self {
diff --git a/service/src/middleware/group.rs b/service/src/middleware/group.rs
index 259f6a25..fe726f7d 100644
--- a/service/src/middleware/group.rs
+++ b/service/src/middleware/group.rs
@@ -26,6 +26,12 @@ use crate::service::Service;
 /// ```
 pub struct Group<S, E>(PhantomData<fn(S, E)>);
 
+impl<S, E> Default for Group<S, E> {
+    fn default() -> Self {
+        unimplemented!("please use Group::new");
+    }
+}
+
 impl<S, E> Group<S, E> {
     pub const fn new() -> Self {
         Self(PhantomData)
diff --git a/unsafe_collection/src/bound_queue/stack.rs b/unsafe_collection/src/bound_queue/stack.rs
index 6b70be6a..6a2ab92a 100644
--- a/unsafe_collection/src/bound_queue/stack.rs
+++ b/unsafe_collection/src/bound_queue/stack.rs
@@ -8,6 +8,12 @@ pub struct StackQueue<T, const N: usize> {
     inner: Bounded<[MaybeUninit<T>; N]>,
 }
 
+impl<T, const N: usize> Default for StackQueue<T, N> {
+    fn default() -> Self {
+        unimplemented!("please use StackQueue::new");
+    }
+}
+
 impl<T, const N: usize> StackQueue<T, N> {
     #[inline]
     pub const fn new() -> Self {
diff --git a/unsafe_collection/src/small_str.rs b/unsafe_collection/src/small_str.rs
index 32e4b392..40141395 100644
--- a/unsafe_collection/src/small_str.rs
+++ b/unsafe_collection/src/small_str.rs
@@ -217,6 +217,12 @@ pub struct SmallBoxedStr {
     inner: Inner,
 }
 
+impl Default for SmallBoxedStr {
+    fn default() -> Self {
+        unimplemented!("please use SmallBoxedStr::new")
+    }
+}
+
 impl SmallBoxedStr {
     #[inline]
     pub const fn new() -> Self {
diff --git a/web/src/app/mod.rs b/web/src/app/mod.rs
index e0c5f854..36a7f791 100644
--- a/web/src/app/mod.rs
+++ b/web/src/app/mod.rs
@@ -519,7 +519,7 @@ impl<R, F> PathGen for App<R, F>
 where
     R: PathGen,
 {
-    fn path_gen(&mut self, prefix: String) -> String {
+    fn path_gen(&mut self, prefix: &str) -> String {
         self.router.path_gen(prefix)
     }
 }
diff --git a/web/src/app/object.rs b/web/src/app/object.rs
index d5624b75..f473efa9 100644
--- a/web/src/app/object.rs
+++ b/web/src/app/object.rs
@@ -23,7 +23,7 @@ where
         where
             I: PathGen,
         {
-            fn path_gen(&mut self, prefix: String) -> String {
+            fn path_gen(&mut self, prefix: &str) -> String {
                 self.0.path_gen(prefix)
             }
         }
diff --git a/web/src/app/router.rs b/web/src/app/router.rs
index 2e4c2e06..242cd82a 100644
--- a/web/src/app/router.rs
+++ b/web/src/app/router.rs
@@ -37,7 +37,7 @@ impl<Obj> PathGen for AppRouter<Obj>
 where
     Router<Obj>: PathGen,
 {
-    fn path_gen(&mut self, prefix: String) -> String {
+    fn path_gen(&mut self, prefix: &str) -> String {
         self.0.path_gen(prefix)
     }
 }
diff --git a/web/src/service/file.rs b/web/src/service/file.rs
index d60d87bb..2c56b264 100644
--- a/web/src/service/file.rs
+++ b/web/src/service/file.rs
@@ -39,7 +39,8 @@ impl ServeDir {
 }
 
 impl PathGen for ServeDir {
-    fn path_gen(&mut self, mut prefix: String) -> String {
+    fn path_gen(&mut self, prefix: &str) -> String {
+        let mut prefix = String::from(prefix);
         if prefix.ends_with('/') {
             prefix.pop();
         }