Question

I’m writing a component-entity system for a game and I hit a bit of a road block. I have a List<Component> derived class call ComponentList that contains all the components for an Entity. I also have a method that returns a component called GetComponent. It does this by a string name.

    public Component GetComponent(string name)
    {
        foreach (var c in this)
        {
            if (c.Name == name)
                return c;
        }
        throw new Exception("Component " + name + " does not exist.");
    }

However, when deriving a class from Component, sticking it into the ComponentList, then pulling it back out, I have to cast in to that type, which is a bit inconvenient.

TestComponent t1 = (TestComponent)Entity.ComponentList.GetComponent("Test1");

I know there is some special, magic way to take a type with < T > but I’m not sure how to use it or, if it even applicable to this situation. Any suggestion?

Answer 1

Code:

public T GetComponent<T>(string name) where T : Component
{
    var result = this.FirstOrDefault(c => c.Name == name);
    if( result == null )
        throw new Exception("Component " + name + " does not exist.");
    return (T) result;
}

Usage:

var testComponent = componentFactory.GetComponent<TestComponent>("Test1");

The language feature enabling this is called generics and you can read more about it on MSDN (and many, many other places; just google for “generics C#”)