[Pythonmac-SIG] appscript Python script preventing logout

[has]

Bill Janssen wrote:

> I'm having a bit of a problem with a Python script I'm running.  It  
> sits
> in a loop and periodically asks "System Events" what's going on, via
> appscript.  The use of appscript turns it into a "foreground process",

Yes, this is annoying and unnecessary behaviour; the problem is that  
the OS will automatically GUI-ify any non-GUI process launched from an  
application bundle if it calls certain system APIs. Appscript uses the  
Process Manager to locate applications and get their process ids, and  
unfortunately that's one of the APIs that has this side effect.

This isn't a problem for Ruby appscript as the 'ruby' interpreter  
isn't packaged as a .app, but the 'python' executables in  
Python.framework's bin directory all use the framework's Python.app  
executable to run the script; hence the automatic promotion when it  
uses Process Manager.

Slightly embarrassing for me, as I was one of those pushing for the  
previous python/pythonw distinction to be eliminated, which it was in  
Python 2.4, but I didn't realise at the time that this would have  
negative as well as positive consequences for appscript. I still think  
allowing the 'python' executable to automatically promote itself was a  
reasonable thing to do, as it's the one that folk habitually use and  
prior to 2.4 this would catch them out when running a script that  
required GUI access, e.g. to display a dialog.

What might be useful if there was also a 'pythonb' executable that  
doesn't provide automatic promotion for benefit of those who know what  
they're doing, although I'm not sure if that falls outside the  
responsibility of the main Python distribution.


> This means that when I try to logout, or reboot, the loginwindow sends
> it a kAEQuitApplication event, but it never replies, which means that
> after 45 seconds loginwindow automatically aborts the logout or
> shutdown.  So, I either need to take that darn rocket out of the Dock
> (which I'd like to be able to do),

If you don't want your python process to be promoted, there are a few  
tricks you could try: target System Events by PID or raw address  
descriptor instead of name/path/bundle id; run your script with a non- 
framework Python; copy Python.app's executable (.../Python.app/ 
Contents/MacOS/Python) to /usr/local/bin/pythonb and use that to run  
your scripts.


> or somehow catch and handle kAEQuitApplication events.


aemreceive's sfba module lets you run an event loop, which you need to  
handle any sort of incoming events, and installs a default 'quit'  
handler for you. It doesn't provide support for Carbon timers or  
background threads, however, so wouldn't be any use to you here. A  
better solution would be to build use Cocoa to provide your script  
with an event loop, as PyObjC isn't subject to the same restrictions  
as sfba.

HTH

has
-- 
Control AppleScriptable applications from Python, Ruby and ObjC:
http://appscript.sourceforge.net