Repeating that: Yes, you can indeed instantiate a python class object (as demo’d by Bob in his attached source code) and call all sorts of instance methods on that object.

Example 1: NSStrings across the bridge are easy if you declare a python function: def myPyStringFun_(self, astring): print "The passed type is " + str(type(aNumber)) you will find that the Objective-C call [mypythonobject myPyStringFun: myNSString] works just fine and the you’ll see: The passed type is

Example 2: we run into a snag trying to pass an int across the bridge
However, if you try to do something like
def myPyIntegerFun_(self, aNumber):
print "The passed type is " + str(type(aNumber))
you’ll be surprised like me to find that
int myInteger = 42;
[mypythonobject myPyIntegerFun: myInteger];
completely fails. The debugger will just exit and freak out with bad address warnings, etc — it won’t even enter the first line of your python function to tell you what was passed into it.

Example 3: Successfully getting an int across the PyObjC bridge
The bridge, as described in the documents works bi-directionally (although bidirectional examples are very difficult to find) using the types on Objective-C end. In other words if you have
def myPyIntegerFun_(self, aNumber):
print "The passed type is " + str(type(aNumber))
and you setup your Objective-C with:
NSNumber * tempint = [[NSNumber alloc] initWithInt:42;
tempString = [gamerObject outputAsBinary:tempint];
you will be rewarded with a happy Python and a log that reads
The passed type is

In summary:
(a) From Objective-C use an NSNumber in your method call to receive an int on the python end of things (or float, I assume).
(b) This was done on Leopard with XCode 3 and Interface Builder 3……
(c) By using Objective-C for the controller aspect, it makes the interface builder hooks and/or bindings straightforward
(d) And more importantly…. this should help keep the Python code clean and (mostly) pure python. I have a bunch of little python tools that I want to throw front ends onto —I’d hate to re-code them with random objc.ivar() stuff littered all over the place — thanks to Bob’s example above and a little trial and lots of error, it’s easy enough to instantiate python objects from the Objective-C side and feed those objects the values they need.

Hope that helps some more of you Python Objective-C XCode people

Now — one important thing to note is that line 57 will compile but will NOT work if you don’t edit the “main.py” file included when you created the XCode project. Specifically you need to make sure to import your python class declarations *BEFORE* the AppHelper line launches everything. In the standard template you’ll see the import pyxxxAppDelegate line.

So far so good — now if I could only find a way to pass an Objective-C (int) to a python instance method.

Now — one important thing to note is that line 57 will compile but will NOT work if you don’t edit the “main.py” file included when you created the XCode project. Specifically you need to make sure to import your python class declarations *BEFORE* the AppHelper line launches everything. In the standard template you’ll see the import pyxxxAppDelegate line.

So far so good — now if I could only find a way to pass an Objective-C (int) to a python instance method.

The problem, is that every single PyObjC example has basically done the *entire* project in Python — or they had some nasty setup scripting and bundle plugin loading crud. This can be a pain in the butt — I’d like to use Objective-C for certain controller areas and leave Python to the data crunching.

Your example seems to work (on the python side) for dynamically loading the python class into Objective C syntax.

Could you please explain some of the details of your AppDelegate.m a little more (in the PyRu sample)? I’m a total noob and the learning curve is steep…. I’m specifically wondering if lines 11-15 are needed for working with the python sublcass. Or — at line 57, Is all that is needed is the NSClassFromString call? Or is it a combination of both.

Once again, since this is the first actual example I found of Objective-C utilizing a Python class — I’m sure there are others out there interested. THANKS.

Traceback (most recent call last):
File “/Users/jayton/Downloads/PyRu/build/Release/PyRu.app/Contents/Resources/main.py”, line 10, in
import objc
ImportError: No module named objc
2007-11-25 14:56:18.660 PyRu[383:10b] /Users/jayton/Downloads/PyRu/AppDelegate.m:48 main() PyRun_SimpleFile failed with file ‘/Users/jayton/Downloads/PyRu/build/Release/PyRu.app/Contents/Resources/main.py’. See console for errors.