C# - event Action parameter limit?

Unity Engine
1

Hello everyone.

So… I am getting an error message, in a quite specific situation…

I have this event:

public event Action<AnimationCurve, AnimationCurve, AnimationCurve, AnimationCurve> onDoSomething;

And this is actually ok… it compiles and works as intended…

However, when I add another AnimationCurve as parameter, like in:

public event Action<AnimationCurve, AnimationCurve, AnimationCurve, AnimationCurve, AnimationCurve> onDoSomething;

I get the error message:
error CS0308: The non-generic type `System.Action’ cannot be used with the type arguments

I believe anyone can try it out and see it…
My question is: is this a know issue? Has anyone ever had this kind of trouble?

I intend to get everything on a list, and send it as a generic list. But that is kind of a surprise for me…
Any thoughts?

2

You can’t use more than 4 parameters in the built-in Action delegate. That’s the limitation of .NET framework 3.5.

You can always create any number of custom delegates, for example:

public delegate void DoSomethingHandler(AnimationCurve a1, AnimationCurve a2, AnimationCurve a3, AnimationCurve a4, AnimationCurve a5);
public event DoSomethingHandler OnDoSomething;

If you prefer generic approach:

public delegate void Action<T1, T2, T3, T4, T5>(T1 arg, T2 arg2, T3 arg3, T4 arg4, T5 arg5);
3

Ah, ok…
Thanks, nikolic!

4

Why dont you create a Value Object class for your multiple parameters and then only pass the VO ?

5

That is a good idea. Or better, if you have an arbitrary number of curves, you could go with params:

public delegate void CurveHandler(params AnimationCurve[] curves);

So you can:

public CurveHandler OnDoSomething = delegate(AnimationCurve[] curves)
{
    foreach (AnimationCurve curve in curves)
    {
        // do something with a curve
    }
};
6

Unfortunately, I am not familiar with the creation of “Value Objects”…
Can you instruct me on that, please?

*btw, the generic list worked fine