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

[Todd B. <tbl...@ma...>]

Yes, I'm working on building a little application with it to make =20
sure it is practical and I think I will release it at the end of summer.

As for the special case behavior - I noticed that you already added =20
half (valueForKey:).  I added the other half. :-)

I spent some time trying to make NSManagedObject work with message =20
sends by overriding repondsToSelector: forwardInvocation: and =20
methodSignatureForSelector:.  NSManagedObject didn't like this at all =20=

and I found myself with a hung program and completely unresponsive =20
debugger.

For what I'm doing, the special case is nice because before I did it, =20=

all the rules had to use setValue:forKey: and this began to feel kind =20=

of ugly.  I can't decide yet if its worth the added complexity.  I =20
got a very boring but useful application working very quickly using =20
coredata, IB, and clips rules, but I an now stuck in Hell with =20
various bits of AppKit as I try to get some custom UI working.

I'll have a firmer opinion with more experience with it.

On Jul 15, 2005, at 5:37 AM, Philippe Mougin wrote:

>
> Tood, this is quite interesting. Are you going to release this =20
> CLIPS/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 =20
> not going to cause unintended problems. Did you encountered any =20
> problem with it ? Do you think it's worth adding to the main F-=20
> Script distribution ? One problem I see with this kind of stuff is =20
> that the more you have such "special case" behavior, the more the =20
> language is 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 =20
>> it.  You can also register a custom parser to parse the rest of =20
>> the function line.  I registered a function named '[' and in the =20
>> parser I just scan to the matching ']' and then pick out the =20
>> variables in the expression and bind them in the FScript symbol =20
>> table.  With this you can write predicates in FScript.  So you =20
>> could write the 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 =20
>> data object has a 'fact' that shadows the values.  KVO allows me =20
>> to keep 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 =20
>> extended it to include mutator support as well.  So even if you =20
>> are using vanilla managed objects, you can still do setFoo: val =20
>> instead of 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 =20
>> a 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 =20
>> sendMsgNoPattern 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 =20
>> hasSuffix: @":"] && 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 =20
>>>> arbitrary objc methods by sending the corresponding NSInvocation =20=

>>>> to a 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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>>
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