Home » Modeling » EMF » derived features with volatile=false, transient=false, changeable=true
| derived features with volatile=false, transient=false, changeable=true [message #415338] |
Wed, 12 December 2007 20:29  |
 Philipp Kutter
Messages: 306
Registered: July 2009 |
Senior Member |
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Hi.
Are such features working?
I asked on the OCL group, and someone asked, whether such a feature
would work.
I do not see any problem for such a feature. Is there one?
Best, Philipp
> 1. Access to a field, if the getter is overwritten
> >
> > We use OCL to define "derived" attributes, as in Christian Damus's
> > Example. These attributes have derive=true, volatile=true,
> > transient=true, changeable=false, and everything works well.
> >
> > Now, in EMF I can have derived attributes with only derive=true,
> > but volatile=false, transient=false, changeable=false. In these
> > attributes a derived getter will typically read the field.
Does this really work? I would expect this to confuse some parts of the EMF
run-time, that would expect a derived property to be unchangeable. I know
that some corners of the GMF run-time make this assumption.
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| Re: derived features with volatile=false, transient=false, changeable=true [message #415340 is a reply to message #415338] |
Wed, 12 December 2007 23:04  |
Ed Merks
Messages: 33140
Registered: July 2009 |
Senior Member |
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Philipp,
Comments below.
Philipp W. Kutter wrote:
> Hi.
> Are such features working?
Where you define working how?
>
> I asked on the OCL group, and someone asked, whether such a feature
> would work.
>
> I do not see any problem for such a feature. Is there one?
You need to write the code for the methods.
>
> Best, Philipp
>
> > 1. Access to a field, if the getter is overwritten
> > >
> > > We use OCL to define "derived" attributes, as in Christian Damus's
> > > Example. These attributes have derive=true, volatile=true,
> > > transient=true, changeable=false, and everything works well.
> > >
> > > Now, in EMF I can have derived attributes with only derive=true,
> > > but volatile=false, transient=false, changeable=false. In these
> > > attributes a derived getter will typically read the field.
>
> Does this really work? I would expect this to confuse some parts of
> the EMF
> run-time, that would expect a derived property to be unchangeable. I
> know
> that some corners of the GMF run-time make this assumption.
It's assumed that derived properties are computed from other values, so
they aren't copied, but as part of being computed they could be set and
hence produce notification...
Ed Merks
Professional Support: https://www.macromodeling.com/
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