[Pyobjc-dev] New NibLoader.py

[Just v. R. <ju...@le...>]

I've attached the current state of NibLoader.py. I would have checked it right
in, if I wasn't getting cvs errors (I think it may be because it takes a while
for new developers to get their permissions set up right, maybe it's a cron job
that runs only once a day?).

Lot's of things have changed, lots of cleanups. Instead if subclassing from a
magic object with a magic metaclass, you now have to specify a metaclass
explicitly:

  from AppKit import NSTableSource
  from AppKit.NibLoader import NibClassBuilder, loadNibFromBundle
  
  loadNibFromBundle("MainMenu")
  
  class PyModel(NSTableSource):
      __metaclass__ = NibClassBuilder

I think this is better as you see right away that something special is going on,
whereas subclassing from a magic object just looks like subclassing. I think
it's good that the magic stands out.

In private mail Jack and I talked about seeing nib files as something similar to
Python modules, so instead of the above one would do (say):

  class PyModel(NSTableSource):
      __metaclass__ = getClassBuilder("MainMenu")

However, this suggests that a nib file is a namespace. It's not. The same class
definition may occur in several nibs, but at runtime there can only exist one,
as Obj-C's class namespace is flat. So I think it's best/better to just keep a
global dict of classes, gathered from all nibs.

(The loading of nibs currently needs to be done with NibLoader.loadNib() or
NibLoader.loadNibFromBundle(), but I think it would be nice to have some
bootstrap code somewhere that just loads all nibs found the the app bundle.)

I've added a simple command line main program, which lets you print an overview
of classes in a set of nibs. I think this could satisfy Ronalds wish for a nib
"documentation" viewer. It's invoked like so:

  python NibLoader.py <path-to-nib> [more paths to nibs]

The program has one option, -t, that will run a simple test instead of printing
the overview.

(Style: I've mostly followed my own naming and coding style. If there's a
consensus about what style the pyobj project should follow, I'd gladly adopt
NibLoader to it. I have some opinions, but this gets religious real fast...)

Just