Does the non-generic version of IEnumerable support deferred execution?

Question

If so, on what .NET Framework versions is it supported?

I have tested this on .NET Framework 4.0 and it works fine:

using System;
using System.Collections.Generic;

public class TestClass
{
    public IEnumerable Defer()
    {
        yield return 1;
        yield return 2;
        yield return 3;
    }
}

Answer 1

Yes, it is supported ever since the yield keyword was. The only difference is that it's more or less IEnumerable<object>, which might lead to inefficiencies if it has to do boxing. Other than that, it's exactly the same.

Answer 2

As the yield keywords are reduced to compiler trickery, presumably this should work. It certainly works for the 2.0 runtime; I'd hesitate to make any statements about 1.1, however.