title: Abstract factory with abstract parameters?
body: <p>I'm trying to design a good entity creation system with an abstract factory (as per <a href="http://www.dofactory.com/Patterns/PatternAbstract.aspx">http://www.dofactory.com/Patterns/PatternAbstract.aspx</a>) but I'm struggling when it comes to instance specific parameters.</p>
  
  <p>For example:
  I have two abstract factories, one for creating a projectile, and one for creating a crate</p>
  
  <p>Now the factory can be either be one instance for each type, which is passed an abstract parameter set from a list (which in the base class would shared material, size etc), type specific parameters would be velocity for a projectile and durability for a crate.</p>
  
  <p>But what I'm struggling with is, in the end when I have this abstract factory method which I call with parameters like a string "BulletProjectile", and "WeakCrate", I need to provide instance specific parameters, and more importantly they are of different types for different factories - for projectiles they would have position and velocity, and crate would just have position.
  A worse scenario is when the user or player is creating a crate or similar object, and is able to define its dimensions. How would I handle this?</p>