Event unsubscription via anonymous delegate [duplicate]

Question

I am using Resharper 5.1 code analysis many a times i get a comment from resharper as

"Event unsubscription via anonymous delegate"

#Part of Code  

if (((bool)e.NewValue))
{
    listView.PreviewTextInput += (o,args) =>
        listView_PreviewTextInput(o,args,listView);
}
else
{
    listView.PreviewTextInput -= (o, args) => 
        listView_PreviewTextInput(o, args, listView);
}

How could i correct or optimze this thing

Answer 1

You can extract the lamdba to a variable:

EventHandler func = (sender, e) =>
    listView_PreviewTextInput(sender, e, listView);

if (((bool)e.NewValue))
{
    listView.PreviewTextInput += func;
}
else
{
    listView.PreviewTextInput -= func;
}