How to replace enumeration with something like interface ID?

Question

Please consider the following interfaces:

interface IFile
{
    // Members
};

interface IAudioFile : IFile
{
    // Members
};

interface IVideoFile : IFile
{
    // Members  
};

enum ContentType
{
    Audio,
    Video
};

interface IProvider
{
    HashSet<ContentType> GetSupportedTypes();
    IList<IFile> GetFiles(ContentType contentType);
};

I think that ContentType enumeration is redundant. Is there any way to use something like interface identifier instead of enumeration type?

Any comments on the interface design are very appreciated.

Answer 1

It really depends on what you're trying to accomplish, but I one options you may want to look at is using generics, so that IProvider is as so

interface IProvider
{
    IList<IFile> GetFiles<T>() where T: IFile;
}

which can be implemented like so

public void ProviderConcrete()
{
    public IList<IFile> GetFiles<T>()
    {
        if(typeof(t) == typeof(IAudioFile))
            .... get Audio files

    }
}

and called like so

public void Caller()
{
    var files = GetFiles<IAudioFile>();
}