Re: [Pyobjc-dev] Embedding in Apps & Loading preferences Bundles

[<bb...@ma...>]

On Monday, November 25, 2002, at 08:02 AM, Ronald Oussoren wrote:
> Some time in the future I will probably try to write whatever is 
> needed to get prefpanes to work. That is probably simular to what is 
> needed to write plugins for programs that use Objective-C classes as 
> plugins (e.g. which is basicly what the system preferences application 
> is doing). I probably won't work on forcing this onto unwilling 
> applications.

I.e. implement an application that implements enough of the various 
classes in Python that are required to make a loaded preferences panel 
work in some place other than System Preferences?  Or create a plugin 
type architecture for new apps?

In the first case, Outside of it being an excellent test of the bridge, 
is the goal to provide the user with standalone prefs apps?   Neat idea.

Key challenge:   The classes that are subsequently subclassed by the 
loaded module must have instance variables that look/feel/act exactly 
like the iVars in the original parent class....

In the second case, there isn't really anything to do -- it already 
"just works" (and is analogous to what a couple of my apps are doing 
when they mixin ObjC code as frameworks within the app wrapper).   You 
will need to create ObjC headers that declare the classes that are 
defined in Python that will be subclassed in the bundle (mostly for the 
iVars, but also just to compile a subclass).  To compile the bundle 
will likely require an '-undefined suppress' option....

> Finding a way to automaticly execute a function when 'our' shared 
> library is loaded will probably the most problematic part of this. 
> That is: Whenever the 'pyobjcextension' shared libary is loaded 
> 'initPyObjCExtension' in that library should run. I haven't looked 
> into this yet and this may well be either trivial or impossible.

Assuming that the target application is ObjC, simply creating a 
+(void)load in a class/category within the dylib should be enough to 
cause a hunk of code to be executing that can call 
-initPyObjCExtension.   There is also a similar mechanism in the pure 
C++ world.

In any case, embedding Python as an extension to existing applications 
would require a build of Python other than Apple's.  Not really a big 
deal -- completely different situation than creating a standalone 
python App (though it would be nice to have an app extension that 
doesn't require a multi-MB download because it includes a python 
distribution).

b.bum