http://www.ideablade.com/forum/ This is an XML content feed of; DevForce Community Forum : DevForce 2010 : Covariance in IEntityQuery<T>? Sat, 11 Apr 2026 21:53:42 -700 Tue, 13 Jul 2010 18:47:53 -700 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 9.69 360 www.ideablade.com/forum/RSS_post_feed.asp?TID=1963 http://www.ideablade.com/forum/forum_images/IdeaBlade_logo_tm.png http://www.ideablade.com/forum/ http://www.ideablade.com/forum/forum_posts.asp?TID=1963&PID=7621#7621 Author: ting
Subject: 1963
Posted: 13-Jul-2010 at 6:47pm

Great idea.  We looked at this last year and really wanted to do it, but Silverlight does not support covariance/contravariance yet and we did not want to break the consistency of our API.

]]> Tue, 13 Jul 2010 18:47:53 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=1963&PID=7621#7621 http://www.ideablade.com/forum/forum_posts.asp?TID=1963&PID=7614#7614 Author: stephenmcd1
Subject: 1963
Posted: 13-Jul-2010 at 11:39am

With the move to .NET4 and it's covariance/contravariance support, I'm wondering if it would be possible to mark IEntityQuery<T> covariant?  It looks like the standard IQueryable<T> and IOrderedQueryable<T> already support covariance.

One reason I'd really like to see this is for situations like the following:

public IEntityQuery<MyBaseEntityType> GetASemiDynamicEntityQuery(bool someCriteria)
{
    if(someCriteria)
        return myEntityManager.Table1;
    else
        return myEntityManager.Table2;
}

As it stands now, the return type would have to be the non-generic IEntityQuery but then I couldn't perform further type-safe filtering or ordering, etc. on the query.

Thanks!
]]> Tue, 13 Jul 2010 11:39:53 -700 http://www.ideablade.com/forum/forum_posts.asp?TID=1963&PID=7614#7614