Avoiding recursion with a setProp handler

[depstein at att.net]

Thanks for the help.  Klaus Major's "pass" command does the job (but it has to be "pass <theCustomPropertyName>", not "pass setProp").

Further experimentation suggests that the MC Help file's stipulation that  "when you set an object's property from within a setprop handler, setprop messages are not sent" applies ONLY if the setProp handler is in that object's own script.  If (as I tried to do) you set a property from within a setProp handler in the script of a stackInUse, another setProp message DOES get sent, with recursion problems.  So the "validation" use of setProp suggested in the Help stack (i.e., a "setProp percent" handler receives as a parameter the value that the property was set to, and then checks and possibly modifies that value) cannot be used "globally"; it can only be used for the object in whose script that setProp handler appears.

David Epstein

Klaus major wrote: 

 > Hi David, 
> 
> > MC 2.5's help stack says that "when you set an object's property from 
> > within a setprop handler, setprop messages are not sent." Is this 
> > true? 
> > 
> > Here's my handler: 
> > 
> > setProp beenChanged whether 
> > put the short date into fld 3 
> ###set the beenChanged of this stack to whether -- (without this, 
> the setProp handler intercepts the calling command, and the property is 
> not set) 
> pass setprop ## ;-) 
> > end setProp 
> 
> > When some other handler commands "set the beenChanged of this stack to 
> > true", my setProp handler gets called. But when I watch the message 
> > watcher, it appears that the second line of my setProp handler is 
> > recursively calling the setProp handler, and I get a "recursion limit 
> > reached" error. 
> > 
> > I realize that I could easily avoid resorting to a setProp handler at 
> > all, but I was tempted by the ease with which I thought it would allow 
> > me to add some behavior I had not thought of when I first wrote a lot 
> > of handlers that "set the beenChanged of this stack." Having come 
> > this far, I would like to understand how to use setProp properly. 
> 
> See above, simply "pass"ing the "setprop" will finally SET THIS PROP :-) 
> 
> Hope this helps. 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.runrev.com/pipermail/metacard/attachments/20040823/a628d3bd/attachment.htm