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rpgoldman / europa-pso

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Purged objects don't notify variables pointing to them... #19

Open GoogleCodeExporter opened 9 years ago

GoogleCodeExporter commented 9 years ago 

See [http://babelfish.arc.nasa.gov/trac/europa/changeset/4967]. The problem
was that:

    * The plan database is cleaned up first, so objects are discarded
    * Because purging is turned on, the object does not notify the plan
database that it has disappeared
    * Therefore, the plan database doesn't do anything about the fact that
there might be variables sitting around pointing to the object (e.g. a
token's 'OBJECT' variable)
    * Later, the constraint engine is purged and if debugging is turned on
(ConstrainedVariable::handleDiscard, specifically), a message tries to
print out info about the variable getting deleted, which includes a pointer
to the object, which has disappeared... 

So, the current situation is that no info is printed during purging. Is
this acceptable, or a sign of design issues we might want to address?

Original issue reported on code.google.com by tristanb...@gmail.com on 9 Sep 2009 at 11:46