[gme-users] Constraint problem

[Jeff Parsons]

If incorrect XML is generated and imported into GME, and the part of the
model corresponding to 
the incorrect XML is not modified by the modeler, what event would
trigger the check?


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	From: gme-users-bounces at list.isis.vanderbilt.edu
[mailto:gme-users-bounces at list.isis.vanderbilt.edu] On Behalf Of Larry
H.
	Sent: Thursday, March 02, 2006 12:15 PM
	To: gme-users
	Subject: RE: [gme-users] Constraint problem
	
	
	Thanks Jeff, this helps clarify my proposal.
	 
	I propose instead the ability to say that a constraint should be
checked exclusively on the associated events.  
	 
	I think that this would put things nicely into the hands of the
meta-modeler.

		-----Original Message-----
		From: gme-users-bounces at list.isis.vanderbilt.edu
[mailto:gme-users-bounces at list.isis.vanderbilt.edu] On Behalf Of Jeff
Parsons
		Sent: Thursday, March 02, 2006 10:56 AM
		To: gme-users
		Subject: RE: [gme-users] Constraint problem
		
		
		What about the case where GME is used with other tools,
for example one that generates
		XML for GME to import. If this tool had a bug and
generated something that violated the
		constraint in question, wouldn't "Check All" be the only
way to catch it?


  _____  

			From: gme-users-bounces at list.isis.vanderbilt.edu
[mailto:gme-users-bounces at list.isis.vanderbilt.edu] On Behalf Of Larry
H.
			Sent: Thursday, March 02, 2006 10:32 AM
			To: gme-users
			Subject: [gme-users] Constraint problem
			
			
			I'm having a problem defining a constraint that
concerns a change in number of children in a container.  My intention is
to check this constraint on an event, like "onlostchild", and to prevent
the action by setting the constraint's Priority=1.  My problem is to
find an approach that does not subsequently trigger a violation when the
user chooses the 'Check All' action of the Constraint Manager.
			 
			It is my current belief that there is no way to
define such a constraint.  The reason is that the focus of this
constraint is "change", whereas the focus of the Constraint Manager, in
general, is "current state".   Constraints concerning "change" typically
involve knowing "state before" and "state after".  Have I failed to
consider something?
			 
			One thing that occurs to me is that the
Constraint Manager might consider not checking constraints on "Check
All" that are checked on events with Priority=1.  The intuition is that,
since such event-based constraints can only result in aborting the
action, there is simply no reason to check them again on "Check All".
Such a feature would allow the desired constraint to be defined quite
simply with a "false" predicate.
			 

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