[Configobj-develop] Making ConfigObj pickle-able

[Jack K. <kj...@gm...>]

Hi all,

sorry, I couldn't wait for ConfigObj to be pickle-able (for pickle protocol
2). So, after some investigation here are some changes
that I've found necessary:

def __newobj__(cls, *args):
    """Required by Section.__reduce__ for using Pickle protocol 2 with
newstyle class. """
    return cls.__new__(cls, *args)


class Section(dict):

    def __reduce__(self):
        d = {}
        d.update(self.__dict__)
        d['parent'] = d['main'] = None      # remove recursive references
        d['sections'] = d['scalars'] = []   # must be empty since we are
going to Section.__setitem__
        return __newobj__, (self.__class__, d), self.__dict__, None,
self.iteritems()

    def __new__(cls, *args, **kws):
        """Partially initialize the object so that it's safe to call
Section.__setitem__ before
        the full states are restored during unpickling.
        """
        inst = super(Section, cls).__new__(cls)

        # Check the args to make sure it's called by __newobj__ before
updating
        # there's probably a better way to verify this....
        if len(args) == 1 and isinstance(args[0], dict):
            d = args[0]
            try:
                if d['parent'] == d['main'] == None:
                    inst.__dict__.update(d)
            except:
                pass
        return inst

then we also need to change just one line in Section.__setitem__:
the line where it says "if not self.main.stringify:", change it to "if
self.main and not self.main.stringify:" since if we are unpickling
self.main will be None, plus there's no need to check the value during
unpickling anyway.

I did some tests on a my configuration, it seems to work. But anyway, the
basic idea I think is that we need to have some states
restored so that during unpickling Section.__setitem__ can rebuild the
section tree structure, and then we complete the unpickling by restoring
the the original states.

Thanks,
Jack