Question

I noticed that I’m often in the need of a container class. For example when working on a particle system, I create a container class Particles which has a member vector<Particle*>. Then I call: Particles* my_particles like my_particles->draw(), and in the Particles.draw() I iterator over the vector<Particle*> and call draw() on each of the particles again. The same works for member functions like update(), addforce() etc.. Now, I’m working on a project and need a collection of Cube on which I need to call tween(), moveTowards() etc..

I know I can use template, but in the case of a template class the member functions need to be knows before. As I want to check if I can make a generic class, that I can use for example both my Cubes and Particles collections.

Someone who has done this before or can give me some advice on this?

Kind regards,
Pollux

Answer 1

The short answer is that you can’t do this in c++. You can, however, use STL algorithms and containers to wrap this behavior up.

First, you’d put your Cube or Particle instances into a std::vector or other container (like you have now).

Then you’d use STL’s std::for_each in combination with std::mem_fun.

It’d result in something like this:

  std::vector<Particle*> V;

  V.push_back(new Particle);
  V.push_back(new Particle);
  V.push_back(new Particle);
  V.push_back(new Particle);

  std::for_each(V.begin(), V.end(), std::mem_fun(&Particle::draw));