On 10/30/09 1:34 PM, Kyle Sluder said:
>> Instead of a value transformer, in your NSManagedObject subclass add a
>> new method called 'timelessDate' which returns a modified version of
>> your 'date' attribute. Then bind your table to 'timelessDate' instead
>> of 'date'. Also use keyPathsForValuesAffectingValueForKey to indicate
>> that 'timelessDate' depends on 'date'.
>
>You could also model this as a transient property.
Yup. Yet I've never been too clear on what the pros and cons of these
two approaches are. In seems in the OP's case, the user would never
want to set this 'timelessDate' and so its really a real-only derived
attribute. I *think* that in such cases, the approach I described is
better. Also, transient properties participate in undo/redo, so I worry
that strange things could happen there. In general, it will also depend
how expensive it is to construct the derived property. Dates are fairly
lightweight, so I doubt it matters here.
--
____________________________________________________________
Sean McBride, B. Eng email@hidden
Rogue Research www.rogue-research.com
Mac Software Developer Montréal, Québec, Canada
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