I think I just ate a Zombie
Well, I think I've figured out the *WTF* part of my little NSZombie problem.
It really boils down to this:
Bind an NSPopubButton (contents) to a Python List object that is an attribute of a python class placed in an NSArray controlled by an NSArrayController and the OC_PythonArray object from PyObjC corresponding to the Python List gets freed too early. (There's a mouthful... Confusing enough?) Wrap that Python List object in an NSArray.alloc().initWithArray_copyItems_([u'the', u'list'], objc.NO) and (I guess) the NSArray...init... adds one more -retain than does OC_PythonArray and the binding doesn't break.
I'm always nervous to call things like this a bug because maybe I'm not *supposed* to be able to do what I'm trying to do in the way that I'm trying to do it, but this one looks like a bug to me. (With the caveat that I am currently learning pyobjc/cocoa and don't always know the *right* way to do things...)
Try it yourself. Here is the simplest example of the bug I can muster. Set BREAKME = True in testObj.py. Run this in the debugger (breakpoint is set on -[NSZombie retain] and NSZombie is enabled already in the project) and you'll see what happens. Set BREAKME = False and everybody is happy.
What did I learn from this:
1. Try to use cocoa objects instead of python objects in code that uses bindings; pay special attention to collections (lists, etc.). At least this *seems* safer because a python object being referenced from cocoa is probably more likely to cause problems than a cocoa object controlled from python. (?) Then again, it's pretty stupid to generalize from one experience...
2. GDB is very useful for debugging pyobjc.
3. There are a lot of nice pyobjc debugging features, but you have to turn them on (See my example project referenced above).
Things I want to know:
1. Is there a way, when one gets the memory address of a pyobjc proxy object (Like OC_PythonArray) from gdb to figure out which python object it's proxying?
2. Is there a reliable way to get (in gdb or pdb) the "Python List Object at 0x03423blahblahblah information from the python object being proxied?
3. Can I compile pyobjc with debugging symbols? GDB without them hurts my brain.