[swift-users] Checking/getting custom objects from a collection

[David Hart]

Unity, the game engine, uses a component system heavily. It uses C# and retrieves components using generic functions. And no, it doesn't force having a single instance of each component class:

http://swiftlang.ng.bluemix.net/#/repl/7be36f2d70a31da3b6ab09b7b89277a4463c23b40c28e1663e56c959a1f3eca8

Crashes the compiler, but that's how I would implement it.

Sent from my iPad
> On 08 Apr 2016, at 02:29, Jens Alfke via swift-users <swift-users at swift.org> wrote:
> 
> I’m not familiar with this design pattern, but it looks like Entity would just contain an array of Component. That makes add() and remove() straightforward.
> 
> I’m not sure about your get() method. It sounds as though the implication is that an entity could only contain a single component of a given class, but that sounds awfully limiting. (If Limb is a Component, then a Spider entity needs eight of them…) I also don’t believe that Swift is dynamic enough to be able to interrogate the classes of components that way at runtime. You could implement that at a higher level by adding a `type` property to ComponentType, that returns some component-type enumeration or maybe a string, and checking component types via that property.
> 
> —Jens
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