[F-Script-talk] Re: Methods in F-Script.

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

Tood, this is quite interesting. Are you going to release this CLIPS/=20
F-Script/Cocoa integration in some form?
About the automatic translation from setValue:val forKey:'foo' to =20
setFoo:val for managed objects, this is something I'm considering =20
adding to F-Script but I want to be sure it will be useful and is not =20=

going to cause unintended problems. Did you encountered any problem =20
with it ? Do you think it's worth adding to the main F-Script =20
distribution ? One problem I see with this kind of stuff is that the =20
more you have such "special case" behavior, the more the language is =20
complex and difficult to master for its users.

Cheers,

Philippe

Le 14 juil. 05 =E0 03:07, Todd Blanchard a =E9crit :

> Huh, seems like a theme.  I've been working on an app based on =20
> integrating the following components:
>
> CoreData - basic object modeling and persistence
> CLIPS - see http://www.ghg.net/clips/CLIPS.html - constraints/=20
> intelligence/rules
> FScript - actions and predicates from CLIPS.
>
> (Yes Philippe - this is based on the thing I showed you at the =20
> Paris Squeaknic a couple years ago).
>
> CLIPS is pretty pluggable - you can install new functions into the =20
> interpreter by handing it a C function pointer and registering it.  =20=

> You can also register a custom parser to parse the rest of the =20
> function line.  I registered a function named '[' and in the parser =20=

> I just scan to the matching ']' and then pick out the variables in =20
> the expression and bind them in the FScript symbol table.  With =20
> this you can write predicates in FScript.  So you could write the =20
> clips rule:
>
> (defrule event-is-active
> ?event<-(Event (startDate ?start&:([NSDate date > ?start])) =20
> (endDate ?end&:([NSDate date < endDate])) (status ~active))
> =3D>
> ([?event setStatus: 'active']))
>
> Which says - match any Event with a startDate later than now, an =20
> endDate earlier than now, and status not set to active
> =3D> (then)
> set the status to active.
>
> The CoreData/CLIPS integration allows you to assert CoreData =20
> objects as 'facts' in the CLIPS knowledge base so the rules can =20
> match them.  This is why the above rule even works.  Each core data =20=

> object has a 'fact' that shadows the values.  KVO allows me to keep =20=

> the fact sync'd with the object.
>
> Lately I've been wishing I could have derived attributes that are =20
> calculated based on other attributes.  This is useful for binding =20
> table columns and such.  To do this, I override valueForKey: in =20
> KBManagedObject (my NSManagedObject subclass) to look up the =20
> userInfo on the attribute description and look for a key called =20
> "value".  This should be an FScript expression that  I toss into a =20
> block and evaluate.  I'm using this to model a Week object where I =20
> just have one real persistent attribute 'sunday'.  The 'monday', =20
> 'tuesday' etc are transient attributes that have FScript =20
> expressions like 'self sunday dateByAddingDays: 1'.  I slap this =20
> into a template that looks like '[:self | %@ ]' and evaluate it as =20
> a block with the managed object as an argument.
>
> I've also notice that the latest FScript has a special case for =20
> NSManagedObject's and "fakes" zero argument message sends that are =20
> the same name as an attribute and calls valueForKey:  I've extended =20=

> it to include mutator support as well.  So even if you are using =20
> vanilla managed objects, you can still do setFoo: val instead of =20
> setValue: val forKey: 'Foo'
>
> This little combination has proven really powerful.  I've build a =20
> working project management app with just clips rules, IB bindings, =20
> and a CoreData model.  It works OK but its pretty vanilla.  I've =20
> been working on sexing up the UI and this is rapidly turning into a =20=

> black hole.  But for quickie apps based on calculations and =20
> constraints, this little framework is da bomb.
>
> I added the following to ExecEngine.m
>
> static NSString* keyFromMutator(NSString* key)
> {
>     if([key hasPrefix: @"set"])
>     {
>         key =3D [[[key substringWithRange: NSMakeRange(3,1)] =20
> lowercaseString]
>                 stringByAppendingString: [key substringWithRange: =20
> NSMakeRange(4,[key length]-5)]];
>     }
>     return key;
> }
>
> and changed the special case for NSMangedObject in sendMsgNoPattern =20=

> to read:
>
>  else if (![receiver isProxy] && [receiver =20
> isKindOfClass:NSClassFromString(@"NSManagedObject")] && =20
> [[[[receiver entity] propertiesByName] allKeys] =20
> containsObject:keyFromMutator(selectorStr)])
>     // We don't support proxy here because it will crash when the =20
> isKindOfClass:NSClassFromString(@"NSManagedObject") message is =20
> executed on Mac OS X < 10.4
>     {
>       if([selectorStr hasPrefix: @"set"] && [selectorStr hasSuffix: =20=

> @":"] && numbersOfArguments =3D=3D 3)
>       {
>         return [receiver performSelector:@selector=20
> (setValue:forKey:) withObject: args[2] withObject: keyFromMutator=20
> (selectorStr)];
>       }
>       else
>       {
>         return [receiver performSelector:@selector(valueForKey:) =20
> withObject:selectorStr];
>       }
>     }
>
>
> On Jul 13, 2005, at 4:55 AM, Marcel Weiher wrote:
>
>>
>> On 13 Jul 2005, at 12:36, Massimiliano Gubinelli wrote:
>>
>>
>>>  recently I wrote some code which allows to override an arbitrary =20=

>>> objc methods by sending the corresponding NSInvocation to a =20
>>> delegate for handling.
>>>
>>
>> Cool.  I wrote something very similar for Objective-Smalltalk, =20
>> which I haven't been able to work much on recently.
>>
>>
>>> My purpose is to use this technique to extend objc classes from =20
>>> an external language (Io, in my case). However I think that such =20
>>> a mechanism can be also useful in F-Script to replace native =20
>>> methods with scripts (and ultimately to be able to define ObjC =20
>>> classes in F-Script).
>>>
>>
>> Yup.
>>
>>
>> --=20
>>
>> Marcel Weiher                Metaobject Software Technologies
>> ma...@me...        www.metaobject.com
>> Metaprogramming for the Graphic Arts.   HOM, IDEAs, MetaAd etc.
>>         1d480c25f397c4786386135f8e8938e4
>>
>>
>>
>>
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