Declare deducted type inside template construct

Author: cmaglie

src/wrapper.h

@@ -100,9 +100,8 @@ class RpcFunctionWrapper<std::function<R(Args...)>>: public IFunctionWrapper {
     }
 };
 
-template<typename F>
-auto wrap(F&& f) -> RpcFunctionWrapper<typename arx::function_traits<typename std::decay<F>::type>::function_type>* {
-    using Signature = typename arx::function_traits<typename std::decay<F>::type>::function_type;
+template<typename F, typename Signature = typename arx::function_traits<typename std::decay<F>::type>::function_type>
+auto wrap(F&& f) -> RpcFunctionWrapper<Signature>* {
     return new RpcFunctionWrapper<Signature>(std::forward<F>(f));
 };