clang -std=c++11 -o components-example components-example.cpp

components-example.cpp

#include <stdio.h>
#include <typeinfo>
#include <unordered_map>

class Foo {
public:
    void dump() { printf("Hello, foo!\n"); }
};

class Bar {
public:
    void dump() { printf("Hello, bar!\n"); }
};

class Entity { // {{{
public:
    template<typename T, typename... Args>
    void addComponent(Args&... args) {
        components_[&typeid(T)] = new T(args...);
    }

    template<typename T>
    T* getComponent() {
        auto i = components_.find(&typeid(T));
        if (i != components_.end())
            return static_cast<T*>(i->second);

        return nullptr;
    }

private:
    std::unordered_map<const std::type_info*, void*> components_;
}; // }}}

int main() {
    Entity e;
    e.addComponent<Foo>();
    e.addComponent<Bar>();

    Foo* foo = e.getComponent<Foo>();
    Bar* bar = e.getComponent<Bar>();

    foo->dump();
    bar->dump();
}