Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!uunet!parcplace!aladdin!ghost
From: ghost@aladdin.com (L. Peter Deutsch)
Newsgroups: comp.lang.postscript
Subject: Question about Level 2 PostScript 'resources'
Message-ID: <39.UUL1.3#5127@aladdin.com>
Date: 3 Jan 91 07:13:53 GMT
Organization: Aladdin Enterprises, Menlo Park, CA
Lines: 23

I just finished reading through section 3.9 of the new PostScript
Language Reference Manual, which is about 'resources' -- sort of like
an object-oriented extension in which the instances of each class
('category') are loaded dynamically from files as needed, and cached
in memory.  This seems like a pretty cool idea to me, a nice
generalization of the way fonts are handled in environments that have
file systems.  However, I'm puzzled about an apparent interaction
between resource category implementation and the global/local memory
management machinery.  The dictionary that defines a resource
category is stored in global memory.  The manual says that each
category must manage global and local instances separately.  However,
objects in global memory can't reference objects in local memory.
This means that the resource category dictionary, which would
otherwise be the obvious place to keep track of the instances, can't
be used to keep track of local instances.  Instead, it appears that
there must be some kind of parallel structure in local memory for
each resource category.  Am I missing something here?

I would appreciate enlightenment on this admittedly obscure topic.

L. Peter Deutsch :: Aladdin Enterprises :: P.O. box 60264, Palo Alto, CA 94306
ghost@aladdin.com ; {uunet,sun,decwrl}!parcplace!aladdin!ghost ; (415)329-0264
	    "Implementation is the sincerest form of flattery."