Beware of using anonymous delegates for event handlers

First found a description of this issue here
There is a problem unsubscribing to an event
Check out the following code:

EventHandler onXXX =
 delegate(object sender, XXXEventArgs e)
 {
  onXXXCallCount++;
  xxxs.Add(e.LastXXX);
 };
... 
m_YYY.OnXXX += onXXX;
...
// The anonymous event handler stays on the event handler until removed
// or the parent object is disposed of!
m_YYY.OnXXX -= onXXX;

Anonymous Delegates And Iterators

c# 2.0 Iterators
Using anonymous delegates

This code: (Note how an anonymous method can access local variables!)

...
XXX mainXXX = ...
...
xxxList.RemoveAll(
    delegate(XXX xxx)
    {
        return xxx.Id == mainXXX.Id; 
    }
);

Does the same as this:

List entriesToRemove = new List();
foreach (XXX xxx in xxxList)
{
    if (xxx.Id == mainXXX.Id)
    {
        entriesToRemove.Add(xxx);
    }
}
foreach (XXX xxx in entriesToRemove)
{
    xxxList.Remove(userToRemove);
}