I'm also interested to know the origin of zombie and its relevance to Squeak. My "guess" is yes for 
MVC and no for Morphic. Anyone know ?

Gary
PS (Model can be further confused with instance variables and methods called "model". [model: 
model: aModel ;-)])
PPS (Even more: An object model has also been known to be called a model)
*Object model : class association diagram plus textual representation of the problem domain.

25/02/02 17:05:59, Nick Brown <maillist at bredon-gill.demon.co.uk> wrote:

>On Mon, 25 Feb 2002 04:54:06 +0000, John Hinsley wrote:
>
>>On Mon, 25 Feb 2002, Gary McGovern wrote:
>>
>>> I believe dependents that persist after the master is destroyed are called zombies and can cause 
a 
>>> memory leak (memory filled with dead objects).
>>
>>I don't think I've ever come across zombie used in that way in an OO (and
>>specifically, Smalltalk) context. Sun's glossary says:
>>
>
>This I think is a bit of an M206-ism. I certainly remembered comming
>across the term zombie there, so I decided to look it up in the course
>notes...
>
><quote>
>There is a class Model (yet another use of the word!) which is almost
>identical class Object from which it inherits. The main difference is
>that a collection of the dependents of instances of Model is held in
>an instance variable. This organisation has the benefit that if you
>destroy the master, the dependents collection will be automatically
>destroyed and, provided no other objects reference these same
>dependents, the dependents can be garbage collected automatically.
>
>If, in contrast, a master that does not hold its own collection of
>dependents is destroyed, its dependents may still be referenced by
>class Object. This may cause the dependents to persist even when no
>other references to them exist and they are effectively useless. In
>the worst case, a steady stream of such happenings can cause a memory
>leak - the memory becomes filled with useless 'dead' objects or
>zombies. Over a long period of time, any object-based system may
>become clogged and refuse to run. Indeed, during prototyping of the
>course, the Course Team stumbled across the odd dead zombie frog. To
>avoid this voodoo-like fate for an object, many programmers who use
>the dependency mechanism prefer to subclass from Model rather than
>from Object   You may like to look at the model class using the class
>browser in the next practical session. If you prefer to stick with
>models that are subclassed from Object and you expect to run your
>program many times, an alternative is for you to give the master
>objects a finalisation or release method that removes all dependents.
>These methods use messages such as removeDependent: when closing the
>program.
></quote>
>
>However, I've never heard of the word 'zombie' anywhere else relating
>to Smalltalk, not that I'm very widely read. I'd be interested to hear
>if the above discussion of zombies is applicable to Squeak.
>
>Nick Brown
>
>
>
>