How to get all generic parameters of class?

Question

I have an abstract class with a few or many (from 1 all the way up to 16) generic parameters like so:

public abstract class ComponentSystem<F1> : ComponentSystemBase
    where F1 : IComponent
{ }

public abstract class ComponentSystem<F1, F2> : ComponentSystemBase
    where F1 : IComponent
    where F2 : IComponent
{ }

public abstract class ComponentSystem<F1, F2, F3> : ComponentSystemBase
    where F1 : IComponent
    where F2 : IComponent
    where F3 : IComponent
{ }

public abstract class ComponentSystem<F1, F2, F3, F4> : ComponentSystemBase
    where F1 : IComponent
    where F2 : IComponent
    where F3 : IComponent
    where F4 : IComponent
{ }

Now I have a base class that contains a list of types like so:

public abstract class ComponentSystemBase
{
    public List<Type> Filters { get; private set; }
    public abstract void Init();
    public abstract void Update();
    protected internal void PopulateFilterList(Type[] filters)
    {
        // oneliner?
        foreach (Type filter in filters)
        {
            Filters.Add(filter);
        }
    }
}

Now my question is, how do I get all the generic parameters in a type array so I can pass it to my function who adds it to the list?

Is there a function to get all the generic parameters, do I have to do it manually for each class?

If something is unclear let me know so i can clarify!

if all parameters are such as `where F1 : IComponent` why don't you use a `List` ? — Cid, Oct 14 '19 at 13:14
Aside from truly generic things like `Func`, `Action` and `ValueTuple` which have good use cases, having long lists of generic arguments is probably a code smell. Note that all of the aforementioned classes have compiler support to easily instantiate them. — Jeroen Mostert, Oct 14 '19 at 13:16
Do you want the parameters ("F1") that the generic class is willing to accept, or the actual arguments ("String") that were provided? — 15ee8f99-57ff-4f92-890c-b56153, Oct 14 '19 at 13:17
@Cid I do it because for the futher implementation it looks nicer :p It is part of an entity component system i am writing. But suggestions are always welcome! — FutureCake, Oct 14 '19 at 13:17
@EdPlunkett I am not sure what you mean :( I am a newb when it comes to c# and programming :) — FutureCake, Oct 14 '19 at 13:19
@EdPlunkett I don't doubt it haha, Always when i try to make something i sink deeper and deeper the further the project progresses ;) — FutureCake, Oct 14 '19 at 13:22
I'm actually quite surprised that this doesn't have a dedicated Stack Overflow Q&A. Only thing I found was [this](https://stackoverflow.com/q/557340/9363973) but the accepted answer on it doesn't answer getting all generic parameters from a class — MindSwipe, Oct 14 '19 at 13:23
Possible duplicate of [Get all types implementing specific open generic type](https://stackoverflow.com/questions/8645430/get-all-types-implementing-specific-open-generic-type) **or** https://stackoverflow.com/questions/557340/how-to-get-the-type-of-t-from-a-member-of-a-generic-class-or-method — Trevor, Oct 14 '19 at 13:30

score 3 · Accepted Answer · answered Oct 14 '19 at 13:14

3

Reflection to the rescue!

Type[] types = GetType().GetGenericArguments();

answered Oct 14 '19 at 13:14

MindSwipe

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How to get all generic parameters of class?

1 Answers1