Question

in what situation will an item in System.Collections.Generic.List not be removed successfully?

From http://msdn.microsoft.com/en-us/library/cd666k3e.aspx:

true if item is successfully removed;
otherwise, false. This method also
returns false if item was not found in
the List(Of T).

The way they phrase it makes me think that it is possible that a Remove operation on an item found in the List(Of T) could actually fail, hence this question.

Answer 1

Looking at the System.Collections.Generic.List source in Reflector, it would appear that the item not being found in the collection is indeed the only way for Remove to return false.

int index = this.IndexOf(item);
if (index >= 0)
{
    this.RemoveAt(index);
    return true;
}
return false;