Question

Can we avoid casting T to Object when placing it in a Cache?

WeakReference necessitate the use of objects. System.Runtime.Caching.MemoryCache is locked to type object.

Custom Dictionaries / Collections cause issues with the Garbage Collector, or you have to run a Garbage Collector of your own (a seperate thread)?

Is it possible to have the best of both worlds?

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I know I accepted an answer already, but using WeakReference is now possible! Looks like they snuck it into .Net 4.

http://msdn.microsoft.com/en-us/library/gg712911(v=VS.96).aspx

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an old feature request for the same.

http://connect.microsoft.com/VisualStudio/feedback/details/98270/make-a-generic-form-of-weakreference-weakreference-t-where-t-class

Answer 1

There’s nothing to stop you writing a generic wrapper around MemoryCache – probably with a constraint to require reference types:

public class Cache<T> where T : class
{
    private readonly MemoryCache cache = new MemoryCache();

    public T this[string key]
    {
        get { return (T) cache[key]; }
        set { cache[key] = value; }
    }

    // etc
}

Obviously it’s only worth delegating the parts of MemoryCache you’re really interested in.