Is there a built-in C# type that allows deferred execution, but not casting back to IQueryable?

Question

Is there a recommended built-in type in C# that collections can be converted/cast to that will still allow deferred execution, but not allow the type to be cast back into IQueryable? (Like IEnumerable<T> can in some cases)

Answer 1

A built in type no but it's pretty easy to do :

public static class Utils
{
    public static IEnumerable<T> AsDefferedEnumerable<T>(this IQueryable<T> Source)
    {
        foreach (var item in Source)
        {
            yield return item;
        }
    }
}

This way you're not returning a casted IQueryable (that could be casted back) but creating a new IEnumerable wrapping it , you don't even need a new type at all for that you just end up with an IEnumerable that will itself enumerate the IQueryable as it is enumerated without exposing it.

Edit : sample of a wrapper object (untested)

public class HideImplementationEnumerable<T>
{
public HideImplementationEnumerable(IEnumerable<T> Source)
{
    this.Source = Source;
}

private IEnumerable<T> Source;

public IEnumerable<T> Value
{
    get
    {
        foreach (var item in Source)
        {
            yield return item;
        }
    }
}
}