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From: johnson@p.cs.uiuc.edu
Newsgroups: comp.lang.smalltalk
Subject: Re: Saving recursive lists to files in
Message-ID: <80500060@p.cs.uiuc.edu>
Date: 8 May 89 14:32:00 GMT
References: <820@sunkisd.CS.Concordia.CA>
Lines: 11
Nf-ID: #R:sunkisd.CS.Concordia.CA:820:p.cs.uiuc.edu:80500060:000:571
Nf-From: p.cs.uiuc.edu!johnson    May  8 09:32:00 1989


storeOn: does not work for circular data structures, because it
tries to do a depth-first traversal of the data structure.  You 
have to write a special version of storeOn: for recursive objects.
The general idea is to write a storeOn:using: method that also
takes a dictionary as an argument.  The dictionary maps each
component of the structure to a name.  The component is only
written out once, but its name can be used many times.

Steve Vegdahl had a nice article explaining this in OOPSLA'86,
and Tektronix versions of Smalltalk include his more general solution.