[Pyobjc-dev] OC_PythonObject broken

[Steven D. M. <sd...@mi...>]

 It looks like the mailings list is working -- with some delay --
as long as I post from the machine I'm subscribed under.
( and since my mac gets a random address & number depending on
where I hook it up to the network, I can't mail from there. )

 Although I'm one of the project admins, I'm pretty new to both
objective-c and the pyobjc module, but since a lot of the revived
interest has been sparked by Mac-OSX, I'm sure there are others
out there trying to learn their way around the code.

 It looks like OC_PythonObject is broken.

 OC_PythonObject is the bridge between python objects and objective-c
objects that implements the NSProxy abstract class and redirects
method calls to it's python methods. ( For example, this would be how you
would subclass NSApplication in Python to make an AppKit application.)

There are a number of things in PyObjC.runtime that you can't touch:
ObjC.lookup_class( 'OC_PythonObject' ) for example, dies with:

Dec 19 18:19:37 python[435] *** Uncaught exception:
<NSInvalidArgumentException> *** -[NSProxy forwardInvocation:] called!


This appears to be the line that crashes:

  if (obj && ([obj isKindOfClass: [NSAutoreleasePool class]] == NO) )


OC_PythonObject's have define an instance method

 - (void)forwardInvocation:(NSInvocation *)anInvocation;

to do this forwarding, but there's no class method, so isKindOfClass:
on the class object causes the crash.

I did a quick patch to try to follow this further:

PythonObject.m
246,253d245
< + (void)forwardInvocation:(NSInvocation *)anInvocation;
< {
<   printf( "%s\n" , [[anInvocation description] cString] );
<   [anInvocation setTarget: [NSObject class]];
<   [anInvocation invoke];
<   return;
< }
<

with that, I can access ObjC.runtime.OC_PythonObject without
crashing.  However, accessing it's method dies:

>>> rt.OC_PythonObject.newWithObject_
Dec 20 15:53:57 python[407] *** Uncaught exception:
<NSInvalidArgumentException> *** -[NSProxy methodSignatureForSelector:]
called!

This was actually pretty expected, as forwardInvocation and
methodSignatureForSelector are documented as the two methods you
MUST override in a concrete NSProxy class.


A few other objects in the runtime will cause a crash. I made a little
script to iterate thru the __objc_classes__ and added them to a skiplist
until I could get thru the whole runtime. They are:

SkipList = ('NSProxy', 'NSConcreteProtocolChecker', 'NSDistantObject',
        'NSInvocationBuilder', 'NSMutableStringProxy' , 'NSProtocolChecker' ,
        '_NSZombie' )


-- Steve Majewski <sd...@Vi...>