LINQ to delete UIElement in SilverLight Children

Question

foreach (UIElement el in GridBoard.Children.ToList())
{
   if (el is Ellipse)
   {
       GridBoard.Children.Remove(el);
   }
}

Is there any LINQ equivalent to do the above? If yes, can please provide the code? Thanks

Answer 1

LINQ is used to query collections rather than cause side-effects. According to MSDN Silverlight doesn't support List<T>'s RemoveAll method but does support the Remove and RemoveAt methods, otherwise you would've been able to write: GridBoard.Children.ToList().RemoveAll(el => el is Ellipse);

You could use LINQ as follows:

var query = GridBoard.Children.OfType<Ellipse>().ToList();
foreach (var e in query)
{
    GridBoard.Children.Remove(e);
}

Alternately, you could traverse your list in reverse and use RemoveAt which would yield some better performance then using Remove:

for (int i = GridBoard.Children.Count - 1; i >= 0; i--)
{
    if (GridBoard.Children[i] is Ellipse)
        GridBoard.Children.RemoveAt(i);
}

So it's not much different than what you had. Perhaps RemoveAll support will make it's way into future Silverlight versions and it would be the best choice.