f-script-talk

[F-Script-talk] newbie questions

[Rainer K. <dri...@ma...>]

Hi all,

I just found F-Script a few days ago and was going through the  
tutorials and reading up what I could find. I also tried looking at  
the list archives, but I get an error when I do that:
"Private archive file not found"
I did subscribe to the list and confirmed, so I think I am properly  
registered.

Now what I wanted to search for was creating classes, having an image  
and a changes file.

For creating classes at least for debugging and experimentation (aka  
hacking ;) I thought it should be possible to create an Objective-C  
class for the "Metaclass". Well, I am probably misunderstanding the  
Metaclass concept still, but this is what I was thinking of:
Just a class with one member that has 2 NSDictionaries, one for the  
members and one for the methods. make sure that it catches all  
unknown methods which get sent to it and then looks them up in your  
dictionary. Would that be possible?

For having an image and a changes file there might be a conflict if  
multiple interpreters are running, at least you would need to find  
some logic, which I could probably look up in other Smalltalks.

I thought somebody probably had these ideas and wishes before, but  
didn't see anything on the website and had no luck with the list  
archive. Could someone kindly give me a few pointers where to look or  
point out why this is silly/won't work?

Best regards!
Rainer Keller

Re: [F-Script-talk] newbie questions

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

Le 19 juin 06 =E0 16:25, Rainer Keller a =E9crit :

> Hi all,
>
> I just found F-Script a few days ago and was going through the
> tutorials and reading up what I could find. I also tried looking at
> the list archives, but I get an error when I do that:
> "Private archive file not found"

Yes, the mailing list has recently suffered several problems =20
following a change of the underlying system. SourceForge, which is =20
operating the mailing list, has been made aware of the problem with =20
the archive and it should be fixed very soon now.

> I did subscribe to the list and confirmed, so I think I am properly
> registered.
>
> Now what I wanted to search for was creating classes, having an image
> and a changes file.
>
> For creating classes at least for debugging and experimentation (aka
> hacking ;) I thought it should be possible to create an Objective-C
> class for the "Metaclass". Well, I am probably misunderstanding the
> Metaclass concept still, but this is what I was thinking of:
> Just a class with one member that has 2 NSDictionaries, one for the
> members and one for the methods. make sure that it catches all
> unknown methods which get sent to it and then looks them up in your
> dictionary. Would that be possible?

Yes. Actually the KFDecorator module adopts this kind of approach =20
(see http://homepage.mac.com/kenferry/software.html#KFDecorator).

Note that F-Script also has a built-in experimental support for =20
creating classes (this functionality is implemented in the JGType =20
class). It uses the Objective-C runtime functions in order to create =20
"real" Objective-C classes on the fly. Here is a basic example where =20
we create a new subclass of NSObject, named MyClass, with three =20
instance variables named a, b and c, and define a simple method named =20=

method1:

 > NSObject subclass:'MyClass' instanceVariableNames:'a b c'
MyClass

 > MyClass
MyClass

 > MyClass setFSBlock:[:self :_cmd| 'Method ' ++ _cmd ++ ' called on =20
' ++ self printString] asInstanceMethod:#method1

 > myInstance :=3D MyClass alloc init

 > myInstance method1
'Method method1 called on <MyClass: 0x4bb69c0>'

There are several limitations in the current implementation: no =20
direct access to instances variables (you have to use KVC), no =20
support for calling super etc.

> For having an image and a changes file there might be a conflict if
> multiple interpreters are running, at least you would need to find
> some logic, which I could probably look up in other Smalltalks.

The saveSpace and loadSpace methods of the class System let you save =20
or load an entire workspace. Not really the same as an image, though.

Best,

Philippe

> I thought somebody probably had these ideas and wishes before, but
> didn't see anything on the website and had no luck with the list
> archive. Could someone kindly give me a few pointers where to look or
> point out why this is silly/won't work?
>
> Best regards!
> Rainer Keller

[F-Script-talk] Intercepting variable access

[Bryan W. <woo...@gm...>]

I'm using F-script  as the “underlying computation engine” for a 
application I’m working on. I've been able to make slight modifications 
to F-script’s behavior using Categories and poseAsClass: until now and I 
need some guidance.

I need to intercept F-script’s variable lookup mechanism to catch 
whenever my special “range syntax” is used. That is, whenever variable 
a1_a12 is referenced I need to catch the lookup and invoke special code 
(that returns an array of variables a1 -> a10) because a1_a10 doesn't 
actually exist and is being used as a shorthand for this kind of behavior.

I originally attempted to override -[FSinterpreter 
objectForIdentifier:found:] only to discover that the interpreter 
doesn't use that method internally. I then downloaded the source and 
found the existence of the SymbolTable class. Which brings me to my 
question:

What SymbolTable method(s) should I override to do what I’m trying to 
accomplish?

So far F-script’s integration with Cocoa/Objc has made making these kind 
of customizations a dream. I’m hoping that my luck continues.

Thanks,
Bryan

Re: [F-Script-talk] newbie questions

[Rainer K. <dri...@ma...>]

Hi Philippe,
>

> Yes. Actually the KFDecorator module adopts this kind of approach
> (see http://homepage.mac.com/kenferry/software.html#KFDecorator).
Yep, I had found KFDecorator (sorry for not mentioning) but was  
missing a way to add member variables.
But I hadn't seen JGType, thanks for the pointer!
>
> There are several limitations in the current implementation: no
> direct access to instances variables (you have to use KVC), no
> support for calling super etc.

understood. But is there a reason that the KVC for the variable names  
and references to super could not be easily done in the compiler?  
Each F-Script class could have a base class, either an objective-C  
class or a previously defined Smalltalk class and two additional  
dictionaries for added member variables and methods. If you then hook  
into the compiler, KVC for the variables could be done automatically  
and super would be available as well. The compiler would just have to  
distinguish if it is still at the Smalltalk layer for resolving  
symbols or already at the boundary to Objective-C.
Does that make sense?

>
> The saveSpace and loadSpace methods of the class System let you save
> or load an entire workspace. Not really the same as an image, though.
Yep, have found that as well (again sorry for not mentioning). But  
image and changes file would be shared between multiple open  
workspaces, changes would grow by both and in my mind the image would  
be part of the resources of the application (once modified probably  
stored in the users Library/Application Support folder and loaded  
automatically on app startup).
Does anybody have an idea in which classes to look to get an idea how  
iamge and changes file are maintained for example in Squeak?

>
> Best,
>
> Philippe

Thanks for the quick answer and pointers!

Rainer