Is it possible to set a Generic for a HashSet?

Question

I want to do something like that, if its possible.

internal sealed class BufferPool<T, K> : K<Buffer<T>>
{
    public BufferPool() : base() {}
    //etc...
}

and then call this class like:

BufferPool<byte, HashSet> buffers;
buffers = new BufferPool<byte, HashSet>(bufferCapacity);

or

BufferPool<byte, List> buffers;
buffers = new BufferPool<byte, List>(bufferCapacity);

Answer 1

You cannot inherit from a type parameter (see How to inherit from a generic parameter? ). What you can do is constrain a type parameter to be of a useful type and a plain constructor, and instantiate an instance inside of your class:

internal sealed class BufferPool<T, K> : IEnumerable<T> where K : IEnumerable<T>, new()
{
    K _bufferImpl = new K();

    public BufferPool() : base() { }
    //etc...
}

Answer 2

That won't work because the compiler needs to know what type/interface your class is inheriting/implementing to determine if your class satisfies the contract requirements of that type. That includes overriding abstract members, implementing interface members, etc.

When you just have a type parameter there, the contract is unknown. This a situation that the compiler does not support.