[PyQt] super()

[Carlos Scheidegger]

>> I would like all the function calls to be consistent so that there's less
>> risks of future gotchas when changing classes to use mixins. Is multiple
>> inheritance in PyQt generally considered a bad idea? What are PyQt best
>> practices when it comes to mixins?
> 
> http://www.riverbankcomputing.com/Docs/PyQt4/pyqt4ref.html#super-and-pyqt-classes
> 
> Phil

Shame on me for not looking it up first. I'm sorry.

I have a question about that paragraph, though. It's not clear by reading the
docs whether this lazy lookup happens on a per-class level or a per-instance
level. I would think logically it should be on a per-class level, but it
doesn't seem that explicitly calling getattr() on the sip-wrapped class is
enough to trigger the lookup.

I tried to make it work with the following class:

class qt_super(object):

    def __init__(self, class_, obj):
        self._class = class_
        self._obj = obj

    def __getattr__(self, attr):
        s = super(self._class, self._obj)
        try:
            meth = getattr(s, attr)
        except AttributeError:
            mro = type(self._obj).mro()

            # This should force a sip method lookup.
            for class_ in mro:
                try:
                    getattr(class_, attr)
                except AttributeError:
                    pass
            s = super(self._class, self._obj)
            meth = getattr(s, attr)
        return meth

but the second call to getattr on the super object still fails. However, this
works:

class qt_super(object):

    def __init__(self, class_, obj):
        self._class = class_
        self._obj = obj

    def __getattr__(self, attr):
        s = super(self._class, self._obj)
        try:
            return getattr(s, attr)
        except AttributeError, e:
            mro = type(self._obj).mro()
            try:
                ix = mro.index(self._class)
            except ValueError:
                raise TypeError("qt_super: obj must be an instance of class")

            for class_ in mro[ix+1:]:
                try:
                    unbound_meth = getattr(class_, attr)
                    return types.MethodType(unbound_meth, self._obj, class_)
                except AttributeError:
                    pass
            raise e

Is there a simple reason? I'm just trying to understand what happens on the
sip side so I don't have to be stupid in public anymore :) (Not that I can
help it, but hey)

Thanks a lot for your patience,
-carlos