title: STL container with different contained types?
body: <p>Let's say I have different types of components which are structs. Maybe I have <code>TransformComponent</code> and <code>RigidBodyComponent</code></p>
  
  <p>Now, this is the problem: I want something like an <code>std::map</code> where you map a component type and an id to a component. The ids are what links components together. What kind of container should I use for this? I can't use an <code>std::map&lt;std::typeindex, std::map&lt;id_t, T&gt;&gt;</code> since the type <code>T</code> depends on which typeindex you use to index the first map.</p>