Using generic interface in a generic class

Question

How force to use class that implement generic interface in class? Is something like this possible?

public interface IGeneric<T>
{
    T Value {get;}
}

//public class MyList<IGeneric<T>> {}//not allowed

I assume you want something like class MyList<T> : IGeneric<T> — MakePeaceGreatAgain
– MakePeaceGreatAgain, Commented Jun 16, 2022 at 11:31
learn.microsoft.com/en-us/dotnet/csharp/language-reference/… — gunr2171
– gunr2171, Commented Jun 16, 2022 at 11:38
No i dont want to implement interface, but use on my custom list as items. — Jarosław Pietras
– Jarosław Pietras, Commented Jun 16, 2022 at 11:40
Then the first option from Enigmativities answer is your solution — MakePeaceGreatAgain
– MakePeaceGreatAgain, Commented Jun 16, 2022 at 11:43
It is possible to create such a class, but I cannot create instances of this class. Example — Jarosław Pietras
– Jarosław Pietras, Commented Jun 16, 2022 at 14:11

Enigmativity · Accepted Answer · 2022-06-17 00:40:02Z

1

Something like this:

void Main()
{
    MyList<string> myList = new MyList<string>(new Generic());
}

public interface IGeneric<T>
{
    T Value { get; }
}

public class MyList<T>
{
    private IGeneric<T> _generic;
    public MyList(IGeneric<T> generic)
    {
        _generic = generic;
    }
}

public class Generic : IGeneric<string>
{
    public string Value => throw new NotImplementedException();
}

Or like this:

void Main()
{
    MyList<Generic, string> myList = new MyList<Generic, string>();
    //Or MyList<IGeneric<string>, string> myList = new MyList<IGeneric<string>, string>();
}

public interface IGeneric<T>
{
    T Value { get; }
}

public class MyList<G, T> where G : IGeneric<T>
{
}

public class Generic : IGeneric<string>
{
    public string Value => throw new NotImplementedException();
}

edited Jun 17, 2022 at 0:40

answered Jun 16, 2022 at 11:31

Enigmativity

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4 Comments

Jarosław Pietras Over a year ago

I can't create class instance, compiler Error CS0311. code MyList<IGeneric<string>> myList = new MyList<IGeneric<string>>();

CompuChip Over a year ago

Probably myList needs to have type MyList<string>, but if you can edit your current interface + class + myList declaration into the question we can answer more specifically.

Jarosław Pietras Over a year ago

MyList<string> don't work. I don't understand "edit your ... declaration to the question". Example

Enigmativity Over a year ago

@JarosławPietras - I've fleshed it out more. And tested that the code runs.

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