[Pyobjc-dev] Need a little direction with delegates and main event loop

[Zachery B. <zb...@ur...>]

Hey, all.

I'm about 80% of the way done with my first PyObjC app. I've based it=20
on Bill's Cocoa-Python Application template. I've done enough tweaking=20=

to both the MyAppDelegate and MainMenu.nib, that I think I'm off-track=20=

a bit. Here is some background info on the app and some particular=20
issues I'm facing:

It's a "nativication" of Casey Duncan's zopeedit.py, a client-side=20
helper app for his External Editor product for Zope [1]. The=20
server-side method marshalls any editor-worthy Zope object (could be=20
text, like Python Scripts, Zope Page Templates, DTML Methods, &c or it=20=

could be images, like gif, jpeg, png, &c) and prepends it with several=20=

lines of RFC822 headers of useful metadata. The client side script=20
strips those off for use internally, writes the remaining file out to a=20=

temp file, and launches an editor based on a lookup of the=20
content-type/meta-type in an editor mapping. This file zopeedit.py=20
works fine as a standalone on Linux/Windows, but it seems that Mac=20
browsers won't accept an arbitrary file (albeit executable) as a valid=20=

helper. This can be somewhat worked around by wrapping the python=20
script in an AppleScript wrapper and using _that_ as the helper app,=20
but it doesn't work for all kinds of editors (notably Carbon apps -=20
with Cocoa apps, I can typically point to the underlying binary in an=20
app bundle - can't seem to do that with Carbon apps, even if they're=20
bundled). So I set about writing my own app in PyObjC, so I could reuse=20=

as much code as possible, and extend it where I can to make a more=20
pleasant UI. After cautiously (and incessantly) pestering Bill, I was=20
able to create an Application Delegate whose openFile_: method I=20
overrode to strip the file, look up the appropriate editor (using=20
NSUserDefaults now instead of ConfigParser), and open the stripped file=20=

with it. Works great.

Some issues:

   =95=A0Now, unfortunately, I need to fulfill the main loop of the =
zopeedit=20
script, and I'm at a bit of a loss on how to do that in the template=20
I'm using. Its __main__.py just jumps right into=20
AppHelper.runEventLoop(). Coupled with the desire to have a bit more=20
control over the event loop, I need to set up some initial app=20
attributes (my current workaround is ugly and doesn't seem to work=20
terribly well anyway).

   =95=A0I'm trying to make a nice UI table of currently open edits =
showing=20
filename and application editing them. I understand the need to=20
delegate the class that will fulfill the various tableView_... methods,=20=

but I'm not sure a) where to make the connections in the nib file, and=20=

b) where to define their implementation in the project.

Here's a rough breakdown of what I'm looking at:

   =95=A0My app has a data structure of some sort holding current edits=20=

(filename, the app that will edit them, and associated metadata used=20
for pushing the changes back to the server) I'd like this to be=20
established in the creation of the app - does this belong in=20
__main__.py? Originally, I tried establishing this in=20
applicationDidFinishLaunching_(), but application_openFile_() is called=20=

before that, so I tried moving it to applicationWillFinishLaunching_(),=20=

and still it seems not to have been made correctly.

   =95=A0This data structure needs to fulfill the NSTableDataSource =
methods=20
to be set as the data source of the table view. Does this data=20
structure need to be accounted for in the nib? Or just in Python code -=20=

meaning, does it need to extend NibClassBuilder.AutoBaseClass?

   =95=A0The original script just runs with a while: 1 loop watching =
over=20
the tempfile it creates and pushes the file back to the server when the=20=

mod time changes. I'd prefer to use notifications (seems more elegant),=20=

but if I can extend the main event loop with this behavior, that would=20=

be an acceptable initial concession.

That's basically it. It's an exceedingly simple python script, but=20
turning it into a full Mac OS X app has proved challenging (mostly=20
because I don't have my Cocoa experience - I'm sure all these feature=20
requirements are very simple to the initiated) :)

Thanks,

Zac

[1] External Editor product:=20
<http://www.zope.org/Members/Caseman/ExternalEditor> - You don't need=20
Zope expertise to understand the client-side aspect.=