Improve and cleanup make_foreign_class()

No need to have two versions of this.
Static assert when users specify ambiguous overloads.
Currently overloads are discriminated only by
parameter count, not types, so we need to enforce this.

examples/math_vector/main.cpp

@@ -21,30 +21,38 @@
 #include "wrenpp/class_manager.hpp"
 #include <string_view>
 #include <algorithm>
-#include <ctime>
-#include <memory>
-#include <vector>
-#include <cstring>
 #include <iostream>
 
 namespace {
 	constexpr std::string_view g_math_vector_src{
 "foreign class MathVector {" R"script(
+	construct new() {}
 	construct new(value) {}
 	construct new(x, y, z) {}
 
 	foreign x
 	foreign y
 	foreign z
+
+	foreign x=(value)
+	foreign y=(value)
+	foreign z=(value)
 }
 )script"};
 
 	constexpr const char g_test_script[] =
 R"script(import "math_vector" for MathVector
-var vec1 = MathVector.new(1.0)
+var vec1 = MathVector.new(15.0)
 var vec2 = MathVector.new(10.0, 20.0, 30.0)
-System.print("vec1: <%(vec1.x), %(vec1.y), %(vec1.z)>")
-System.print("vec2: <%(vec2.x), %(vec2.y), %(vec2.z)>")
+var vec3 = MathVector.new()
+System.print("vec1 constructed from single value: <%(vec1.x), %(vec1.y), %(vec1.z)>")
+System.print("vec2 constructed from three values: <%(vec2.x), %(vec2.y), %(vec2.z)>")
+System.print("vec3 default constructed: <%(vec3.x), %(vec3.y), %(vec3.z)>")
+
+vec3.x = 3.5
+vec3.y = vec2.x / vec2.z
+vec3.z = vec1.x + vec2.y / 4.0
+System.print("vec3 modified by scripting: <%(vec3.x), %(vec3.y), %(vec3.z)>")
 )script";
 
 	class MathVector {
@@ -61,9 +69,12 @@ System.print("vec2: <%(vec2.x), %(vec2.y), %(vec2.z)>")
 		double x() const { return m_x; }
 		double y() const { return m_y; }
 		double z() const { return m_z; }
+		void set_x(double x) { m_x = x; }
+		void set_y(double y) { m_y = y; }
+		void set_z(double z) { m_z = z; }
 
 	private:
-		double m_x, m_y, m_z;
+		double m_x{}, m_y{}, m_z{};
 	};
 
 	class MyConf : public wren::DefConfiguration {
@@ -82,14 +93,24 @@ System.print("vec2: <%(vec2.x), %(vec2.y), %(vec2.z)>")
 
 int main() {
 	using wren::make_method_bindable;
+	using wren::make_foreign_class;
 
 	MyConf conf;
 	wren::VM vm(&conf, nullptr);
 	vm.callback_manager()
+		.add_callback(false, "math_vector", "MathVector", "x=(_)", make_method_bindable<&MathVector::set_x>())
+		.add_callback(false, "math_vector", "MathVector", "y=(_)", make_method_bindable<&MathVector::set_y>())
+		.add_callback(false, "math_vector", "MathVector", "z=(_)", make_method_bindable<&MathVector::set_z>())
 		.add_callback(false, "math_vector", "MathVector", "x", make_method_bindable<&MathVector::x>())
 		.add_callback(false, "math_vector", "MathVector", "y", make_method_bindable<&MathVector::y>())
 		.add_callback(false, "math_vector", "MathVector", "z", make_method_bindable<&MathVector::z>());
-	vm.class_manager().add_class_maker("math_vector", "MathVector", &wren::make_overloaded_foreign_class<MathVector, double, std::tuple<double, double, double>>);
+
+	vm.class_manager()
+		.add_class_maker("math_vector", "MathVector", &make_foreign_class<MathVector,
+			double, //single value constructor
+			std::tuple<double, double, double>, //x,y,z constructor
+			std::tuple<> //default constructor
+		>);
 
 	vm.interpret("main", g_test_script);
 

include/wrenpp/detail/construct_foreign_class.hpp

@@ -71,6 +71,16 @@ namespace wren {
 			}
 		};
 
+		template <typename T>
+		struct ForeignParamHelper {
+			static constexpr std::size_t argument_count = 1;
+		};
+
+		template <template <typename...> class Pack, typename... PackArgs>
+		struct ForeignParamHelper<Pack<PackArgs...>> {
+			static constexpr std::size_t argument_count = sizeof...(PackArgs);
+		};
+
 		template <typename T>
 		struct ForeignClassHelper<T> {
 			static bool construct (VM& vm, int cardinality, void* memory) {
@@ -95,10 +105,31 @@ namespace wren {
 				ForeignClassHelper<T, Args...>::construct(vm, vm.slot_count() - 1, memory);
 			}
 		}
+
+		template <std::size_t Search, std::size_t... Values>
+		struct AssertIfDuplicateValues {
+			static_assert(sizeof...(Values) == 0, "Code bug?");
+		};
+
+		template <std::size_t Search, std::size_t Value, std::size_t... Values>
+		struct AssertIfDuplicateValues<Search, Value, Values...> : AssertIfDuplicateValues<Search, Values...>, AssertIfDuplicateValues<Value, Values...> {
+			static_assert(Search != Value, "Constructor overloads with the same argument counts are not currently allowed");
+			static constexpr std::size_t value = 1;
+		};
+
+		template <typename... Args>
+		constexpr void static_assert_all_packs_are_unique() {
+			if constexpr (sizeof...(Args) > 0) {
+				constexpr auto dummy = AssertIfDuplicateValues<ForeignParamHelper<Args>::argument_count...>::value;
+				static_assert(dummy == 1); //always true
+			}
+		}
 	} //namespace detail
 
 	template <typename T, typename... Args>
-	inline foreign_class_t make_overloaded_foreign_class() {
+	inline foreign_class_t make_foreign_class() {
+		detail::static_assert_all_packs_are_unique<Args...>();
+
 		foreign_class_t ret;
 		ret.allocate = [](VM& vm) {
 			void* const mem = vm.set_slot_new_foreign(0, 0, sizeof(T));
@@ -116,9 +147,4 @@ namespace wren {
 
 		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