Re: [F-Script-talk] Subclassing NSManagedObject

[Philippe M. <pm...@ac...>]

You're right, F-Script check for the supported keys before generating =20=

a valueForKey: message. This is done in the function =20
"sendMsgNoPattern", in file ExecEngine.m (search for NSManagedObject).

Note that you may be able to have it work the way you want without =20
customizing F-Script: instead of relying on "valueForUndefinedKey:" =20
you could rely on the "forwardInvocation:" and =20
"methodSignatureForSelector:" methods (see the documentation for =20
NSObject). They act like "valueForUndefinedKey:" but on a more =20
general level (i.e., work for any message, not just for KVC =20
properties). At first glance the documentation for =20
"forwardInvocation:" can be somewhat misleading... In fact, you are =20
not restricted to forwarding messages. You can do whatever you want =20
and manipulate the passed in NSInvocation to return the result you want.

Best,

Philippe


Le 5 janv. 07 =E0 14:50, Tim McDonald a =E9crit :

> Happy New Year
>
> I'm playing around with an implementation of f-script which will make
> use of a subclass of NSManagedObject.
>
> I'm writing a core data program contains an "Items" entity linked via
> a one to many relationship to a "Characteristics" entity. The
> "Characteristics" entity has two attributes name and value. Each
> "Item" may contain a number of characteristics which I was planning
> on accessing by subclassing NSManagedObject so I can make use of the
> valueForUndefinedKey method to the correct value based upon if the
> message matched the name attribute, i.e.
>
> 	> Characteristics test
>
> which would return something like:
>
> 	{100, 200}
>
> Unfortunately, after setting everything up all I got was:
>
> 	> Characteristics test
> 	error: an instance of SDTManagedObject does not respond to =
"test"
>
> After playing around with various bit and pieces I finally got it to
> work using
>
> 	> Characteristics valueForKey: 'test'
> 	{100, 200}
>
> However I'd prefer to use the more concise commands (ie. ">
> Characteristics test"). I'm guessing that these don't work because F-
> script  first checks what keys an object support's before sending any
> message. Could you give me any pointer on what this may be as I think
> I'll have to customise this method as well?
>
> Best Regards
>
> Tim
>
> ----------------------------------------------------------------------=20=

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