C++ where T : Type

test.cpp

#include "where_T.h"
#include <iostream>

struct IComponent {
  virtual void init = 0;
  virtual void update(double dt) = 0;
  virtual void render() = 0;
}

struct ConcreateComponent : public IComponent {
  void init() {}
  void update(double dt) {}
  void render() {}
}

struct NotComponent {
  void init() {}
  void update(double dt) {}
  void render() {}
}

struct IComponentCollection {
  where_T(IComponent, void) add(T component, bool overwrite);
	where_T(IComponent, T) find();
	where_T(IComponent, T) contains();
	where_T(IComponent, void) remove();
};

struct ComponentCollection : IComponentCollection {
  where_T(IComponent, void) add(T component, bool overwrite) {
		std::cout << "add template working" << std::endl;
	}
	where_T(IComponent, T) find();
	where_T(IComponent, T) contains() {
		std::cout << "contains template working" << std::endl;
		return true;
	}
	template <class T>
  typename std::enable_if<std::is_base_of<Type, void>::value, Return>::type remove() {
		std::cout << "remove template working" << std::endl;
		return true;
	}
};

where_T(IComponent, T) ComponentCollection::find() {
	std::cout << "find template working" << std::endl;
	return T();
}

int main() {
  auto collection = ComponentCollection();
  auto comp = ConcreateComponent();
	auto notComp = NotComponent();
	collection.add(comp, false);
	collection.contains<Comp>();
	collection.find<Comp>();
	collection.remove<Comp>();
	collection.contains<NotComp>();
}

where_T.h

#include <type_traits>

#define where_T(Type, Return) \
  template <class T> \
	typename std::enable_if<std::is_base_of<Type, T>::value, Return>::type