Question

I created an EvaluateAttribute, and I want it to accept various IEvaluators specified like this:

[Evaluate(CatEvaluator, DogEvaluator)]
public void someMethod()
{
}

Since CatEvaluator and DogEvaluator are types, I set up my attribute class like this:

   public class EvaluateAttribute<T> : Attribute where T:IAccessEvaluator

and constructor:

public EvaluateAttribute(params T [] accessEvaluators)
{
    _accessEvaluators = accessEvaluators;
}

C# doesn’t like generics and attributes though, it would seem. Is there a solution to this?

I want my attribute to instantiate each type with CreateInstance and run an evaluate method specific in IAccessEvaluator.

Answer 1

You probably don’t need to use generics if you just want to pass classes implementing IAccessEvaluator. Just change the signature to

public EvaluateAttribute(params IAccessEvaluator [] accessEvaluators)
{
    _accessEvaluators = accessEvaluators;
}

Reread your question. You’re using types like objects, so my first impression was to write the above answer. If you need to annotate types, you should have a look at the comment on your question (by MUG4N).

public EvaluateAttribute(params Type [] accessEvaluators)
{
    _accessEvaluators = accessEvaluators;
}

[Evaluate(typeof(CatEvaluator), typeof(DogEvaluator)]
public SomeClass{ }

and change _accessEvaluators to Type[]