Re: [Pyobjc-dev] PyObjC newbie questions

[Ronald O. <ous...@ci...>]

On Saturday, May 3, 2003, at 23:20 Europe/Amsterdam, Gary Robinson 
wrote:

> Hello everyone,
>
> I'm a PyObjC newbie hoping to get some info.
>
> I have a couple decade's worth of programming experience plus solid
> experience in Python development on Solaris.
>
> I have no experience with Cocoa or Objective C.
>
> I am interested in using PyObjC to create a small Cocoa application, 
> mostly
> because  I want to get it done quickly and don't want to have to master
> Objective C, and in particular, don't want to deal with reference 
> counting
> etc. Also, I very much like Python's syntax and the libraries that 
> come with
> it.
>
> It sounds like PyObjC could allow me to do what I want to do, but I 
> have
> some concerns. I am hoping that someone here can address them for me.
>
> 1) refcounts.html in the PyObjC docs files says "Other than in very 
> special
> situations you should never have to worry about reference counts. Those
> special methods mostly seem to involve zombie objects that are no 
> longer
> reachable from normal code, but will perform some action before really 
> dying
> at the end of the current pass through the event loop."
>
> OK, but does that mean I can do things in such a way that I KNOW that 
> Python
> is handling them? That is, is there a programming style I can use such 
> that,
> if I rigorously follow it, I will know I am not creating the kind of 
> zombie
> object mentioned above, and am not creating other violations the
> python-handles-it capability?
>
> In other words, if I don't take the time to develop a deep 
> understanding of
> Objective C's memory management, can I rely on something other than 
> random
> chance to keep me out of trouble?  Or is that knowledge actually 
> required?

You don't have to know about Objective-C's memory management, the 
bridge performs all memory management you need. The sentence you quote 
has to do with some deep Objective-C magic, which is nothing you should 
run in to (it's like metaclasses in Python, they are there but you 
probably shouldn't tell newbies about them).



>
> 2) tutorial.html in the docs file says: "It is even possible to 
> include all
> of Python (or, if you are using Apple's Python 2.2, all the bits of 
> Python
> that are non-standard), this gives you an application that is 
> distributable
> to anyone in the world (as long as they have Mac OS X 10.2)! 
> Unfortunately,
> the exact details of this procedure are not streamlined enough for 
> inclusion
> in this tutorial at this point in time."
>
> OK, but is there a way I can find out how to do it? I would be 
> creating an
> app that I will be hoping a lot of non-developers will download and 
> run.

Some of the example applications include a script named buildapp.py. 
This will build the application without using Project Builder. If you 
copy the contents of /usr/lib/python2.2/site-packages/PyObjC into the 
Resources directory of the application bundle (such as 
TableModel.app/Contents/Resources for the TableModel example), you'll 
end up with a standalone application.

The same thing should be possible with the Project Builder templates. 
If I recall correctly those will create standalone applications if you 
build the install target.

>
> 3) While I've done an solid amount of Python programming on Solaris, I 
> have
> used it only minimally on the Mac. This app would need to control a 
> separate
> standard OS X app locally via AppleEvents, receive XML-RPC requests 
> from
> other machines, and send XML-RPC requests to other machines.
>
> Any forseeable problems doing all that with Python's standard 
> libraries and
> PyObjC?

XML-RPC should not be a problem, see the example 'WebServicesTool'. 
I've never used AppleEvents before, I can't say anything about that. I 
do know that MacPython contains AppleScript related modules, but to use 
those you probably need to use Python 2.3.

Ronald