Hi folks:� I am trying to understand ImageSegment methods like activeClasses, swapOutInactiveClasses, discoverActiveClasses among others. One of the comments of those methods says:

"NOTE:� discoverActiveClasses uses Squeak's ability to detect and recover from faults due to a nil method dictionary.� It staches the method dict in with the organization during the time when discovery is in progress (Gag me with a spoon).� This is why the faults need to be cleared promptly before resuming normal work with the system.� It is also important that classes *do not* refer directly to their method dictionary, but only via the accessor message."

So, it seems to HACK (it forces a fault) this MD fault recover to discover inactive classes and other things. Ok, forget that hack for a moment.

What questions is, what are these faults?� Why a method dictionary can be in nil ? How is this produced ? And how is it fixed?

I saw for example this:

Behaviour>>methodDict
�� methodDict == nil ifTrue: [self recoverFromMDFaultWithTrace].
�� ^ methodDict

But again...how can that be nil ???

Thank you very much.

Marian