Re: [Help-smalltalk] environment/shared pool search order?

[Paolo Bonzini]

Stephen Compall wrote:
> STSymbolTable uses an IdentitySet to store pool dictionaries and 
> environments.  This is fine ordinarily, but loses the search order 
> imposed by find_class_variable in sym.c.  Perhaps what is needed is the 
> semantics of an "ordered identity set"?

That's right.  The simplest way to implement such a thing is
to subclass IdentitySet, adding something like

initialize: size
    super initialize: size.
    orderedCollection := OrderedCollection new: size.

remove: anObject ifAbsent: aBlock
    self shouldNotImplement

primAt: anIndex put: anObject
    orderedCollection addLast: anObject

do: aBlock
    orderedCollection do: aBlock


The best way to do so would be the other way round:
subclass OrderedCollection, wrapping all the "add" methods
with a test for inclusion (using the hashed collection),
and redefining #includes: so that it uses the hashed
collection.  This would have the advantage that you
could use the same class for both OrderedSet and
OrderedIdentitySet.

Either choice is fine with me.

Paolo