[squeak-dev] On class/metaclass coupling

Ralph Johnson johnson at cs.uiuc.edu
Tue Dec 8 13:53:51 UTC 2009

If you haven't done this already, you should look up Actalk, which was
a version of Smalltalk that let you have many classes with the same


I never used Actalk, I just read the papers.  It was an interesting
and worthwhile experiment, but I wasn't convinced that the change was
worthwhile.  But perhaps we just need to figure out more to do with

What you are saying is a little different.  You are just complaining
about hardcoding the assumption that each clas has a unique metaclass.
 All you are really asking is to get rid of the "thisClass" variable.
I don't see any harm in that.  I bet that "new" is rarely called more
than once on any metaclass, and that one time is during the creation
of the class/metaclass pair.  The bigger issue is that when you
evaluate and print the expression "Object class", what happens is that
it computes the metaclass and then asks the metaclass to print itself,
which it does by fetching the name of its sole instance and appending
" class" to it.  In other words, a metaclass does not have a name, but
derives its name from the name of its sole instance.  But this doesn't
have to be fast, either.  You could call allInstances to find out the
instance and get its name.  My guess is that it would hardly be

Making this change would not cause metaclasses to have more than one
instance, but would make it easier for people to change things so it


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