Python interactive navigation around nested functions

[Dima Kogan <dima@secretsauce.net>]

Hi. The current way python-mode handles nested functions seems wrong to
me. I had thought that it was a bug, but the test suite explicitly
checks for the current behavior, so I want to ask about it here before
proposing a patch.

This is the first check in the (python-nav-beginning-of-defun-1) test in
test/automated/python-tests.el. Let's say you have a python buffer:

    def decoratorFunctionWithArguments(arg1, arg2, arg3):
        '''print decorated function call data to stdout.

        Usage:

        @decoratorFunctionWithArguments('arg1', 'arg2')
        def func(a, b, c=True):
            pass
        '''

        def wwrap(f):
            print 'Inside wwrap()'
            def wrapped_f(*args):
                print 'Inside wrapped_f()'
                print 'Decorator arguments:', arg1, arg2, arg3
                f(*args)
                print 'After f(*args)'
            return wrapped_f
        return wwrap

The point is on "return wrapped_f". The user then hits C-M-a to navigate
to the beginning of the current function. The point is unambiguously
inside wwrap() and not inside wrapped_f(), so I claim it should end up
at the "def wwrap(f)" line. However the current behavior (and that test
suite check) say it should end up on "def "wrapped_f()".

This seems wrong. In fact, there are two different "go-to-previous-def"
functions: one that supposedly handles nested defuns
(python-nav-beginning-of-defun) and one that doesn't
(python-nav-backward-defun), and it doesn't make sense that they both do
the same thing here. 

I propose to make C-M-a to go to "def wwrap" here. I already have the
patches ready, but the test case is giving me pause.

dima