You might have heard about weak references which are used when listener functions for events in Action Script are being set. In 2006 gskinner was wondering why all the listeners were not set in weak reference mode. Some of guys on Habrahabr in comments to my article about functions contexts insisted on the fact that weak references are the bad practice and all the operations related to their removal you should do only manually.
I have known about them for a long time because I try to keep tabs on all Adobe’s news but I understood how it works recently just after using Flex Builder’s profiler. Instead of retelling background information I will give you an example where you might see how useful these weak references may be:
