pyobjc-dev

[Pyobjc-dev] PyObjC newbie questions

[Gary R. <gro...@tr...>]

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?

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.

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?


Thank you in advance for any and all insight...

--Gary

-- 
[http://ThisURLEnablesEmailToGetThroughOverzealousSpamFilters.org]

Gary Robinson
CEO
Transpose, LLC
gro...@tr...
207-942-3463
http://www.transpose.com
http://radio.weblogs.com/0101454

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

Re: [Pyobjc-dev] PyObjC newbie questions

[Gary R. <gro...@tr...>]

Ronald,

Many thanks for your input!

I think the AppleScript part shouldn't be a problem because I believe Cocoa
supplies the means to create AppleEvents, so I should be use Cocoa for that
part...

Another thing, though. What about people who are running 10.1? Is it
possible to include the Python interpreter itself in the app using
buildapp.py so that such a user doesn't need to already have Python?

--Gary

-- 
[http://ThisURLEnablesEmailToGetThroughOverzealousSpamFilters.org]

Gary Robinson
CEO
Transpose, LLC
gro...@tr...
207-942-3463
http://www.transpose.com
http://radio.weblogs.com/0101454


> From: Ronald Oussoren <ous...@ci...>
> Date: Sun, 4 May 2003 01:10:02 +0200
> To: Gary Robinson <gro...@tr...>
> Cc: <pyo...@li...>
> Subject: Re: [Pyobjc-dev] PyObjC newbie questions
> 
> 
> 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
> 

Re: [Pyobjc-dev] PyObjC newbie questions

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

On Sunday, May 4, 2003, at 03:06 Europe/Amsterdam, Gary Robinson wrote:

> Ronald,
>
> Many thanks for your input!
>
> I think the AppleScript part shouldn't be a problem because I believe 
> Cocoa
> supplies the means to create AppleEvents, so I should be use Cocoa for 
> that
> part...
>
> Another thing, though. What about people who are running 10.1? Is it
> possible to include the Python interpreter itself in the app using
> buildapp.py so that such a user doesn't need to already have Python?

builapp.py uses the bundlebuilder module which supports creating 
standalone applications ('buildapp.py --standalone build'). The bad 
news is that PyObjC currently doesn't work on 10.1, mostly because none 
of the developers have access to a 10.1 system.

Ronald

Re: [Pyobjc-dev] PyObjC newbie questions

[Gary R. <gro...@tr...>]

> The bad 
> news is that PyObjC currently doesn't work on 10.1, mostly because none
> of the developers have access to a 10.1 system.

Hmm. Too bad it didn't happen to work on 10.1 anyway. But it is hard to keep
extra machines around with obsolete OS's.

If I don't use PyObjC for this app I'll definitely look forward to using it
when more of the user base can access such apps. But for this application I
think I can't afford to lose the 10.1 user base...

Let me ask a quick somewhat off-topic question. Online I saw an example, I
think from Apple, of an AppleScript Studio application that invoked a Perl
daemon to do stuff that Perl was more capable of doing... communication was
via SOAP (using AppleScript's SOAP calls on the AppleScript Studio side). It
seemed quite easy.

That seems like an approach I could take for this, except using a Python app
as the daemon. The AppleScript Studio app would invoke it and tell it to
shut itself down when it isn't needed.

Do you know if I can write a Python app of that nature and bundle it with
the Python interpreter into a single executable under 10.1 and 10.2? Would
other python installations the user may have interfere in any way? Any
problem with making such an app "faceless" in the sense of having no
presence in the dock?

Many thanks for all your help!

--Gary

-- 
[http://ThisURLEnablesEmailToGetThroughOverzealousSpamFilters.org]

Gary Robinson
CEO
Transpose, LLC
gro...@tr...
207-942-3463
http://www.transpose.com
http://radio.weblogs.com/0101454