“命名”模板类实例化

Question

In my game engine, I've created a pretty funky component-based entity system which allows me to define entity types as a combination of components, specified as template arguments, eg:

typedef Entity<Locateable, Collidable, Renderable /* etc */ > SomeEntity;

This works fine, until I need to uniquely identify an instantiation of a template definition..

typedef Entity<Locateable, Collidable, Renderable> Missile;
typedef Entity<Locateable, Collidable, Renderable> Bullet;

typeid(Missile) == typeid(Bullet) // sad panda :( 

Obviously they are they same type, but I'd like them not to be, ideally I'd like to give each a string name, something like this:

// Invalid code...
typedef Entity<"Missile", Locateable, Collidable, Renderable> Missile;
typedef Entity<"Bullet", Locateable, Collidable, Renderable> Bullet;

That way I could access a static name() method later on. But that doesn't work because the strings need to be statically instantiated. I tried to do this too, but lambdas also aren't allowed...

// More invalid code...
typedef Entity<[]()-> char* { return "Missile"; }, Locateable, Collidable, Renderable> Missile;
typedef Entity<[]()-> char* { return "Bullet"; }, Locateable, Collidable, Renderable> Bullet;

So, my question is, is there some neat trick that will allow me to name the template definitions inline?

Answer 1

Instead of just using typedefs, you could use simple inheritance, maybe something like this:

class Missile : public Entity<Locateable, Collidable, Renderable>
{
public:
    static std::string name() { return "Missile"; }
};

class Bullet: public Entity<Locateable, Collidable, Renderable>
{
public:
    static std::string name() { return "Bullet"; }
};

Answer 2

The whole point of ECS is to be pointlessly dynamic. If it's not pointlessly dynamic, then why bother using ECS in the first place? Just use regular classes and composition.