[Python-Dev] [Python-3000] Pre-pre PEP for 'super' keyword
ironfroggy at gmail.com
Mon Apr 30 15:09:35 CEST 2007
On 4/30/07, Tim Delaney <tcdelaney at optusnet.com.au> wrote:
> I've been working on improved super syntax for quite a while now - my
> original approach was 'self.super' which used _getframe() and mro crawling
> too. I hit on using bytecode hacking to instantiate a super object at the
> start of the method to gain performance, which required storing the class in
> co_consts, etc. It turns out that using a metaclass then makes this a lot
> > However, I seem to think that if the __this_class__ PEP goes through,
> > your version can be simplified as well. No tricky stuffy things in
> > cells would be needed, but we can just expand the super 'keyword' to
> > __super__(__this_class__, self), which has been suggested at least
> > once. It seems this would be much simpler to implement, and it also
> > brings up a second point.
> > Also, I like that the super object is created at the beginning of the
> > function, which my proposal couldn't even do. It is more efficient if
> > you have multiple super calls, and gets around a problem I completely
> > missed: what happens if the instance name were rebound before the
> > implicit lookup of the instance object at the time of the super call?
> You could expand it inline, but I think your second point is a strong
> argument against it. Also, sticking the super instance into a cell means
> that inner classes get access to it for free. Otherwise each inner class
> would *also* need to instantiate a super instance, and __this_class__ (or
> whatever it's called) would need to be in a cell for them to get access to
> it instead.
> BTW, one of my test cases involves multiple super calls in the same method -
> there is a *very* large performance improvement by instantiating it once.
Note that I would now advocate the creation of the super object at the
beginning of function, and when I talk about expanding super to
super(__this_class__, self) I do mean doing it at the beginning of the
function, just like you are saying, so we're in agreement here.
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