diff --git a/include/wrenpp/class_manager.hpp b/include/wrenpp/class_manager.hpp
index 457108b..e364b0a 100644
--- a/include/wrenpp/class_manager.hpp
+++ b/include/wrenpp/class_manager.hpp
@@ -22,6 +22,7 @@
 #include <unordered_map>
 #include <string>
 #include <type_traits>
+#include <functional>
 
 namespace wren {
 	namespace detail {
@@ -73,7 +74,7 @@ namespace wren {
 	} //namespace detail
 
 	class ClassManager {
-		typedef foreign_class_t(*make_foreign_class_t)();
+		typedef std::function<foreign_class_t()> make_foreign_class_t;
 		typedef std::unordered_map<detail::ClassNameOwning, make_foreign_class_t, detail::ClassNameHash, detail::ClassNameEqual> ClassMap;
 	public:
 		ClassManager();
diff --git a/include/wrenpp/detail/construct_foreign_class.hpp b/include/wrenpp/detail/construct_foreign_class.hpp
new file mode 100644
index 0000000..cffc504
--- /dev/null
+++ b/include/wrenpp/detail/construct_foreign_class.hpp
@@ -0,0 +1,124 @@
+/* Copyright 2020-2022, Michele Santullo
+ * This file is part of wrenpp.
+ *
+ * Wrenpp is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Wrenpp is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with wrenpp.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "wrenpp/vm.hpp"
+#include "seters_getters.hpp"
+#include <utility>
+#include <tuple>
+#include <cassert>
+
+namespace wren {
+	namespace detail {
+		template <typename T, int... Indices, typename... Args>
+		inline void construct_single (
+			std::integer_sequence<int, Indices...>,
+			VM& vm,
+			void* memory
+		) {
+			new(memory) T{get<Args>(vm, Indices + 1)...};
+		}
+
+		template <typename T, typename... Args>
+		struct ForeignClassHelper;
+
+		template <typename T, template <typename...> class Pack, typename... PackArgs, typename... Args>
+		struct ForeignClassHelper<T, Pack<PackArgs...>, Args...> {
+			static bool construct (VM& vm, int cardinality, void* memory) {
+				using std::make_integer_sequence;
+
+				//search by number of parameters.
+				//once we find a tuple-like parameter that contains the right
+				//number of types we invoke construct_single() with those types.
+				constexpr int pack_size = static_cast<int>(sizeof...(PackArgs));
+				if (pack_size == cardinality) {
+					construct_single<T>(make_integer_sequence<int, pack_size>{}, vm, memory);
+					return true;
+				}
+				else {
+					return ForeignClassHelper<T, Args...>::construct(vm, cardinality, memory);
+				}
+			}
+		};
+
+		template <typename T, typename LoneArg, typename... Args>
+		struct ForeignClassHelper<T, LoneArg, Args...> {
+			static bool construct (VM& vm, int cardinality, void* memory) {
+				using std::make_integer_sequence;
+
+				if (1 == cardinality) {
+					construct_single<T>(make_integer_sequence<int, 1>{}, vm, memory);
+					return true;
+				}
+				else {
+					return ForeignClassHelper<T, Args...>::construct(vm, cardinality, memory);
+				}
+			}
+		};
+
+		template <typename T>
+		struct ForeignClassHelper<T> {
+			static bool construct (VM& vm, int cardinality, void* memory) {
+				using std::make_integer_sequence;
+
+				assert(cardinality == 0);
+				construct_single<T>(make_integer_sequence<int, 0>{}, vm, memory);
+				return true;
+			}
+		};
+
+		template <typename T, typename... Args, int... Indices>
+		inline void find_params_and_construct_foreign_class (
+			std::integer_sequence<int, Indices...> seq,
+			VM& vm,
+			void* memory
+		) {
+			if constexpr (sizeof...(Args) == 0) {
+				construct_single<T>(seq, vm, memory);
+			}
+			else {
+				ForeignClassHelper<T, Args...>::construct(vm, vm.slot_count() - 1, memory);
+			}
+		}
+	} //namespace detail
+
+	template <typename T, typename... Args>
+	inline foreign_class_t make_overloaded_foreign_class() {
+		foreign_class_t ret;
+		ret.allocate = [](VM& vm) {
+			void* const mem = vm.set_slot_new_foreign(0, 0, sizeof(T));
+
+			detail::find_params_and_construct_foreign_class<T, Args...>(
+				std::make_integer_sequence<int, sizeof...(Args)>{},
+				vm,
+				mem
+			);
+		};
+		ret.finalize = [](void* mem) {
+			const auto cale = static_cast<T*>(mem);
+			cale->~T();
+		};
+
+		return ret;
+	}
+
+	template <typename T, typename... Args>
+	inline foreign_class_t make_foreign_class() {
+		return make_overloaded_foreign_class<T, std::tuple<Args...>>();
+	}
+} //namespace wren
diff --git a/include/wrenpp/detail/seters_getters.hpp b/include/wrenpp/detail/seters_getters.hpp
new file mode 100644
index 0000000..bbe17ce
--- /dev/null
+++ b/include/wrenpp/detail/seters_getters.hpp
@@ -0,0 +1,170 @@
+/* Copyright 2020-2022, Michele Santullo
+ * This file is part of wrenpp.
+ *
+ * Wrenpp is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * Wrenpp is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with wrenpp.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "wrenpp/vm.hpp"
+#include <string_view>
+#include <vector>
+#include <tuple>
+
+namespace wren {
+	namespace detail {
+		template <typename T> struct GetTypeToRetType;
+		template <typename T> using GetTypeToRetType_t = typename GetTypeToRetType<T>::type;
+
+		template <typename T> struct TType { typedef T type; };
+
+		template<typename T>struct GetTypeToRetType{
+			static_assert(not std::is_fundamental_v<T>, "User type expected");
+			static_assert(not std::is_pointer_v<T>, "Unexpected pointer type");
+			typedef std::remove_cv_t<T>* type;
+		};
+		template<>struct GetTypeToRetType<const char*> : TType<const char*>{};
+		template<>struct GetTypeToRetType<double> : TType<double>{};
+		template<>struct GetTypeToRetType<bool> : TType<bool>{};
+		template<>struct GetTypeToRetType<std::pair<const char*,int>> : TType<std::pair<const char*,int>> {};
+		template<>struct GetTypeToRetType<int> : TType<int>{};
+		template<>struct GetTypeToRetType<std::size_t> : TType<std::size_t>{};
+		template<>struct GetTypeToRetType<std::string> : TType<std::string>{};
+		template<>struct GetTypeToRetType<std::string_view> : TType<std::string_view>{};
+		template<>struct GetTypeToRetType<std::vector<char>> : TType<std::vector<char>>{};
+
+#if __cpp_concepts >= 201907
+		template <typename T>
+		concept ConstCharTuple = requires {
+			std::same_as<std::remove_cv_t<T>, Handle> or
+			std::same_as<std::remove_cv_t<T>, ModuleAndName>;
+		};
+#endif
+
+#if __cpp_concepts >= 201907
+		template <typename... Outs, int... Indices, ConstCharTuple... Params>
+#else
+		template <typename... Outs, int... Indices, typename... Params>
+#endif
+		inline std::tuple<detail::GetTypeToRetType_t<Outs>...> variables_impl (
+			VM& vm,
+			std::integer_sequence<int, Indices...>,
+			Params&&... modules_names
+		) {
+			if constexpr (sizeof...(Outs) == 0) {
+				return {};
+			}
+			else {
+				static_assert(sizeof...(Params) == sizeof...(Outs), "Expected a module/name pair per requested output");
+				static_assert(sizeof...(Outs) == sizeof...(Indices), "Mismatching index count");
+
+				vm.ensure_slots(sizeof...(Params));
+				(variable(vm, modules_names, Indices), ...);
+				return std::tuple<detail::GetTypeToRetType_t<Outs>...>(get<Outs>(vm, Indices)...);
+			}
+		}
+	} //namespace detail
+
+	void set (VM& vm, int slot_num, const char* value);
+	void set (VM& vm, int slot_num, double value);
+	void set (VM& vm, int slot_num, bool value);
+	void set (VM& vm, int slot_num, std::nullptr_t);
+	void set (VM& vm, int slot_num, const char* bytes, std::size_t length);
+	void set (VM& vm, int slot_num, const std::string& value);
+	void set (VM& vm, int slot_num, std::string_view value);
+	void set (VM& vm, int slot_num, const std::vector<char>& value);
+	void set (VM& vm, int slot_num, const char* beg, const char* end);
+	void set (VM& vm, int slot_num, int value);
+	void set (VM& vm, int slot_num, std::size_t value);
+	std::string_view slot_string_view (VM& vm, int slot_num);
+	template <typename T> detail::GetTypeToRetType_t<T> get (VM& vm, int slot_num);
+	template <typename T> T* foreign (VM& vm, int slot_num);
+
+#if __cpp_concepts >= 201907
+	template <typename... Outs, detail::ConstCharTuple... Params>
+#else
+	template <typename... Outs, typename... Params>
+#endif
+	std::tuple<detail::GetTypeToRetType_t<Outs>...> variables(VM& vm, Params&&... modules_names);
+
+	inline void set (VM& vm, int slot_num, const char* value) {
+		vm.set_slot_string(slot_num, value);
+	}
+
+	inline void set (VM& vm, int slot_num, double value) {
+		vm.set_slot_double(slot_num, value);
+	}
+
+	inline void set (VM& vm, int slot_num, bool value) {
+		vm.set_slot_bool(slot_num, value);
+	}
+
+	inline void set (VM& vm, int slot_num, std::nullptr_t) {
+		vm.set_slot_null(slot_num);
+	}
+
+	inline void set (VM& vm, int slot_num, const char* bytes, std::size_t length) {
+		vm.set_slot_bytes(slot_num, bytes, length);
+	}
+
+	inline void set (VM& vm, int slot_num, const std::string& value) {
+		vm.set_slot_string(slot_num, value.c_str());
+	}
+
+	inline void set (VM& vm, int slot_num, std::string_view value) {
+		vm.set_slot_bytes(slot_num, value.data(), value.size());
+	}
+
+	inline void set (VM& vm, int slot_num, const std::vector<char>& value) {
+		vm.set_slot_bytes(slot_num, value.data(), value.size());
+	}
+
+	inline void set (VM& vm, int slot_num, int value) {
+		vm.set_slot_double(slot_num, static_cast<double>(value));
+	}
+
+	inline void set (VM& vm, int slot_num, std::size_t value) {
+		vm.set_slot_double(slot_num, static_cast<double>(value));
+	}
+
+	template <typename T>
+	inline T* foreign (VM& vm, int slot_num) {
+		T* obj = static_cast<T*>(vm.slot_foreign(slot_num));
+		return obj;
+	}
+
+#if __cpp_concepts >= 201907
+	template <typename... Outs, detail::ConstCharTuple... Params>
+#else
+	template <typename... Outs, typename... Params>
+#endif
+	inline std::tuple<detail::GetTypeToRetType_t<Outs>...> variables(VM& vm, Params&&... modules_names) {
+		return detail::variables_impl<Outs...>(vm, std::make_integer_sequence<int, sizeof...(Outs)>(), std::forward<Params>(modules_names)...);
+	}
+
+	template <typename T>
+	inline detail::GetTypeToRetType_t<T> get (VM& vm, int slot_num) {
+		return foreign<T>(vm, slot_num);
+	}
+
+	template<> const char* get<const char*> (VM& vm, int slot_num);
+	template <> double get<double> (VM& vm, int slot_num);
+	template <> bool get<bool> (VM& vm, int slot_num);
+	template <> std::pair<const char*, int> get<std::pair<const char*,int>> (VM& vm, int slot_num);
+	template<> int get<int> (VM& vm, int slot_num);
+	template<> std::size_t get<std::size_t> (VM& vm, int slot_num);
+	template<> std::string get<std::string> (VM& vm, int slot_num);
+	template <> std::string_view get<std::string_view> (VM& vm, int slot_num);
+	template <> std::vector<char> get<std::vector<char>> (VM& vm, int slot_num);
+} //namespace wren
diff --git a/include/wrenpp/vm_fun.hpp b/include/wrenpp/vm_fun.hpp
index 6d6815b..c6371d3 100644
--- a/include/wrenpp/vm_fun.hpp
+++ b/include/wrenpp/vm_fun.hpp
@@ -23,40 +23,18 @@
 #	include "guess_class_name.hpp"
 #endif
 #include "wren_types.hpp"
+#include "detail/construct_foreign_class.hpp"
+#include "detail/seters_getters.hpp"
 #include <string>
 #include <string_view>
-#include <vector>
 #include <type_traits>
 #include <cstddef>
 #include <utility>
 
 namespace wren {
 	namespace detail {
-		template <typename T> struct GetTypeToRetType;
-		template <typename T> using GetTypeToRetType_t = typename GetTypeToRetType<T>::type;
-
-#if __cpp_concepts >= 201907
-		template <typename T>
-		concept ConstCharTuple = requires {
-			std::same_as<std::remove_cv_t<T>, Handle> or
-			std::same_as<std::remove_cv_t<T>, ModuleAndName>;
-		};
-#endif
-
-		template <typename T, int... Indices, typename... Args>
-		inline void construct_foreign_class (
-			std::integer_sequence<int, Indices...>,
-			void* memory
-		);
 	} //namespace detail
 
-#if __cpp_concepts >= 201907
-	template <typename... Outs, detail::ConstCharTuple... Params>
-#else
-	template <typename... Outs, typename... Params>
-#endif
-	std::tuple<detail::GetTypeToRetType_t<Outs>...> variables(VM& vm, Params&&... modules_names);
-
 	template <typename R, typename... Args>
 	R call (VM& vm, const Handle& object, const Handle& method, const Args&... args);
 
@@ -69,9 +47,6 @@ namespace wren {
 	template <typename R, std::size_t N, typename... Args>
 	R call (VM& vm, const ModuleAndName& object, const char (&method)[N], const Args&... args);
 
-	template <typename T, typename... Args>
-	foreign_class_t make_foreign_class();
-
 	template <typename T, typename... Args>
 	T* make_foreign_object(VM& vm, const ModuleAndName& mn, Args&&... args);
 
@@ -84,66 +59,12 @@ namespace wren {
 	foreign_method_t make_method_bindable();
 
 	void interpret (VM& vm, const std::string& module_name, const std::string& script);
-	void set (VM& vm, int slot_num, const char* value);
-	void set (VM& vm, int slot_num, double value);
-	void set (VM& vm, int slot_num, bool value);
-	void set (VM& vm, int slot_num, std::nullptr_t);
-	void set (VM& vm, int slot_num, const char* bytes, std::size_t length);
-	void set (VM& vm, int slot_num, const std::string& value);
-	void set (VM& vm, int slot_num, std::string_view value);
-	void set (VM& vm, int slot_num, const std::vector<char>& value);
-	void set (VM& vm, int slot_num, const char* beg, const char* end);
-	void set (VM& vm, int slot_num, int value);
-	void set (VM& vm, int slot_num, std::size_t value);
-	std::string_view slot_string_view (VM& vm, int slot_num);
-	template <typename T> detail::GetTypeToRetType_t<T> get (VM& vm, int slot_num);
-	template <typename T> T* foreign (VM& vm, int slot_num);
 	void variable(VM& vm, const ModuleAndName& mod_and_name, int slot);
 	void variable(VM& vm, const Handle& handle, int slot);
 	void variable_ensure_slot(VM& vm, const ModuleAndName& mod_and_name, int slot);
 	void variable_ensure_slot(VM& vm, const Handle& handle, int slot);
 
 	namespace detail {
-		template <typename T> struct TType { typedef T type; };
-
-		template<typename T>struct GetTypeToRetType{
-			static_assert(not std::is_fundamental_v<T>, "User type expected");
-			static_assert(not std::is_pointer_v<T>, "Unexpected pointer type");
-			typedef std::remove_cv_t<T>* type;
-		};
-		template<>struct GetTypeToRetType<const char*> : TType<const char*>{};
-		template<>struct GetTypeToRetType<double> : TType<double>{};
-		template<>struct GetTypeToRetType<bool> : TType<bool>{};
-		template<>struct GetTypeToRetType<std::pair<const char*,int>> : TType<std::pair<const char*,int>> {};
-		template<>struct GetTypeToRetType<int> : TType<int>{};
-		template<>struct GetTypeToRetType<std::size_t> : TType<std::size_t>{};
-		template<>struct GetTypeToRetType<std::string> : TType<std::string>{};
-		template<>struct GetTypeToRetType<std::string_view> : TType<std::string_view>{};
-		template<>struct GetTypeToRetType<std::vector<char>> : TType<std::vector<char>>{};
-
-#if __cpp_concepts >= 201907
-		template <typename... Outs, int... Indices, ConstCharTuple... Params>
-#else
-		template <typename... Outs, int... Indices, typename... Params>
-#endif
-		inline std::tuple<detail::GetTypeToRetType_t<Outs>...> variables_impl (
-			VM& vm,
-			std::integer_sequence<int, Indices...>,
-			Params&&... modules_names
-		) {
-			if constexpr (sizeof...(Outs) == 0) {
-				return {};
-			}
-			else {
-				static_assert(sizeof...(Params) == sizeof...(Outs), "Expected a module/name pair per requested output");
-				static_assert(sizeof...(Outs) == sizeof...(Indices), "Mismatching index count");
-
-				vm.ensure_slots(sizeof...(Params));
-				(variable(vm, modules_names, Indices), ...);
-				return std::tuple<detail::GetTypeToRetType_t<Outs>...>(get<Outs>(vm, Indices)...);
-			}
-		}
-
 		template <typename T>
 		inline void set_single_for_call (VM& vm, int slot, const T& value) {
 			set(vm, slot, value);
@@ -204,76 +125,12 @@ namespace wren {
 
 		template <typename T, typename R, typename... Args, R(T::*Method)(Args...)> struct MakeMethodBindable<Method> : MakeMethodBindableConstNonConst<T, R, Method, Args...> {};
 		template <typename T, typename R, typename... Args, R(T::*Method)(Args...)const> struct MakeMethodBindable<Method> : MakeMethodBindableConstNonConst<T, R, Method, Args...> {};
-
-		template <typename T, typename... Args, int... Indices>
-		inline void construct_foreign_class (
-			std::integer_sequence<int, Indices...>,
-			VM& vm,
-			void* memory
-		) {
-			new(memory) T{get<Args>(vm, Indices + 1)...};
-		}
 	} //namespace detail
 
-#if __cpp_concepts >= 201907
-	template <typename... Outs, detail::ConstCharTuple... Params>
-#else
-	template <typename... Outs, typename... Params>
-#endif
-	inline std::tuple<detail::GetTypeToRetType_t<Outs>...> variables(VM& vm, Params&&... modules_names) {
-		return detail::variables_impl<Outs...>(vm, std::make_integer_sequence<int, sizeof...(Outs)>(), std::forward<Params>(modules_names)...);
-	}
-
 	inline void interpret (VM& vm, const std::string& module_name, const std::string& script) {
 		return vm.interpret(module_name.c_str(), script.c_str());
 	}
 
-	inline void set (VM& vm, int slot_num, const char* value) {
-		vm.set_slot_string(slot_num, value);
-	}
-
-	inline void set (VM& vm, int slot_num, double value) {
-		vm.set_slot_double(slot_num, value);
-	}
-
-	inline void set (VM& vm, int slot_num, bool value) {
-		vm.set_slot_bool(slot_num, value);
-	}
-
-	inline void set (VM& vm, int slot_num, std::nullptr_t) {
-		vm.set_slot_null(slot_num);
-	}
-
-	inline void set (VM& vm, int slot_num, const char* bytes, std::size_t length) {
-		vm.set_slot_bytes(slot_num, bytes, length);
-	}
-
-	inline void set (VM& vm, int slot_num, const std::string& value) {
-		vm.set_slot_string(slot_num, value.c_str());
-	}
-
-	inline void set (VM& vm, int slot_num, std::string_view value) {
-		vm.set_slot_bytes(slot_num, value.data(), value.size());
-	}
-
-	inline void set (VM& vm, int slot_num, const std::vector<char>& value) {
-		vm.set_slot_bytes(slot_num, value.data(), value.size());
-	}
-
-	inline void set (VM& vm, int slot_num, int value) {
-		vm.set_slot_double(slot_num, static_cast<double>(value));
-	}
-
-	inline void set (VM& vm, int slot_num, std::size_t value) {
-		vm.set_slot_double(slot_num, static_cast<double>(value));
-	}
-
-	template <typename T>
-	inline T* foreign (VM& vm, int slot_num) {
-		T* obj = static_cast<T*>(vm.slot_foreign(slot_num));
-		return obj;
-	}
-
 	template <typename R, typename... Args>
 	inline R call (VM& vm, const Handle& object, const Handle& method, const Args&... args) {
 		detail::set_for_call<Args...>(std::make_integer_sequence<int, sizeof...(Args)>(), vm, args...);
@@ -314,21 +171,6 @@ namespace wren {
 		return call<R, N, Args...>(vm, obj_handle, method, args...);
 	}
 
-	template <typename T, typename... Args>
-	inline foreign_class_t make_foreign_class() {
-		foreign_class_t ret;
-		ret.allocate = [](VM& vm) {
-			void* const mem = vm.set_slot_new_foreign(0, 0, sizeof(T));
-			detail::construct_foreign_class<T, Args...>(std::make_integer_sequence<int, sizeof...(Args)>{}, vm, mem);
-		};
-		ret.finalize = [](void* mem) {
-			const auto cale = static_cast<T*>(mem);
-			cale->~T();
-		};
-
-		return ret;
-	}
-
 	template <typename T, typename... Args>
 	inline T* make_foreign_object(VM& vm, const ModuleAndName& mn, Args&&... args) {
 		variable(vm, mn, 0);
@@ -352,19 +194,4 @@ namespace wren {
 	inline foreign_method_t make_method_bindable() {
 		return detail::MakeMethodBindable<V>::make();
 	}
-
-	template <typename T>
-	inline detail::GetTypeToRetType_t<T> get (VM& vm, int slot_num) {
-		return foreign<T>(vm, slot_num);
-	}
-
-	template<> const char* get<const char*> (VM& vm, int slot_num);
-	template <> double get<double> (VM& vm, int slot_num);
-	template <> bool get<bool> (VM& vm, int slot_num);
-	template <> std::pair<const char*, int> get<std::pair<const char*,int>> (VM& vm, int slot_num);
-	template<> int get<int> (VM& vm, int slot_num);
-	template<> std::size_t get<std::size_t> (VM& vm, int slot_num);
-	template<> std::string get<std::string> (VM& vm, int slot_num);
-	template <> std::string_view get<std::string_view> (VM& vm, int slot_num);
-	template <> std::vector<char> get<std::vector<char>> (VM& vm, int slot_num);
 } //namespace wren
diff --git a/src/class_manager.cpp b/src/class_manager.cpp
index 859f6ef..2bf6fe0 100644
--- a/src/class_manager.cpp
+++ b/src/class_manager.cpp
@@ -92,7 +92,7 @@ namespace wren {
 
 		auto it_found = m_classes.find(TempClassName{module_name, class_name});
 		if (m_classes.cend() != it_found)
-			return (*it_found->second)();
+			return it_found->second();
 		else
 			return {nullptr, nullptr};
 	}