Re: [Pyobjc-dev] Re: Subclassing NSCell?

[Mitch C. <mit...@ea...>]

On Wednesday, May 14, 2003, at 12:55  PM, Ronald Oussoren wrote:
> I usually look for the right process-id from the shell and then start 
> 'gdb /usr/local/bin/pyton THEPID' (THEPID being the process-id).
>
> Are you using the Project Builder templates? These use /usr/bin/python 
> unless you change the bin-python-main.m file.

Well, thanks to the in-line documentation y'all wrote in 
bin-python-main.m,
I wasn't having trouble figuring out which python executable to target 
with gdb,
or which process ID to attach to.  My problem turned out to be that I 
wasn't  setting
DYLD_FRAMEWORK_PATH properly,  so gdb couldn't load the Python dynamic 
library.

With DYLD_FRAMEWORK_PATH set to refer to the system frameworks 
directory,
like so:
	DYLD_FRAMEWORK_PATH=/Library/Frameworks
gdb was happy again.


Now I'm stuck trying to learn why [methinfo getArgumentTypeAtIndex:i] 
(libffi_support.m,
line 323) would return an invalid value for i == 3, when 
methinfo->_nargs == 4.

It seems to be extracting a bogus id for the second argument to
drawInteriorWithFrame_inView_, which is supposed to be the control view 
into
which the NSCell subclass draws.

The signature in methinfo matches that generated for my
drawInteriorWithFrame_inView_ method, to wit:

NSMethodSignature: types=v@:{_NSRect={_NSPoint=ff}{_NSSize=ff}}@ 
nargs=4 sizeOfParams=160 returnValueLength=0;

or, as gdb puts it:
(gdb) print *methinfo
$14 = {
   isa = 0xa07ed538,
   _types = 0x46ec60 "v@:{_NSRect={_NSPoint=ff}{_NSSize=ff}}@\000"...,
   _nargs = 4,
   _sizeofParams = 160,
   _returnValueLength = 0,
   _parmInfoP = 0x46ec10,
   _fixup = 0x0,
   _reserved = 0x0
}

The code is failing on the retobject assignment in the following code 
fragment
(near line 673 in pythonify_c_value, in Modules/objc/objc_support.m).
obj has the "out of bounds" value 0x3f800000, so I guess the problem
starts before the attempt to invoke __pyobjc_PythonObject__:

	case _C_ID:
	{
		id obj = *(id *) datum;

		if (obj == nil) {
			retobject = Py_None;
			Py_INCREF (retobject);
		} else {
			retobject = [obj  __pyobjc_PythonObject__];


I'm not sure where to go from here.  Any suggestions?
--
Mitch