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From: geremy condra on 7 Dec 2009 12:14 On Mon, Dec 7, 2009 at 12:05 PM, M.-A. Lemburg <mal(a)egenix.com> wrote: > geremy condra wrote: >> On Mon, Dec 7, 2009 at 7:51 AM, M.-A. Lemburg <mal(a)egenix.com> wrote: >>> Terry Reedy wrote: >>>> M.-A. Lemburg wrote: >>>> >>>>> Integrating an easy-to-use graph library into the collections >>>>> module (and it's C companion) is good idea. >>>>> >>>>>>> This would have to be written in C, though, >>>>>> That's currently in the works, along with database backing. >>>>>> We'd welcome any help though... hint, hint... >>>> >>>> The current thinking among deveopers is that new modules should be >>>> written and maintained in Python, which all implementations can use, >>>> with speed-critical parts written in C for speed and imported by the >>>> Python code. >>> >>> I don't think you are speaking for Python developers in general. >> >> I believe he's referring to the core developers. > > I was as well, being one of them :-) Misunderstanding: 2, Me: 0... moving on ;) How interested are you in a C port of graphine? I haven't had any specific requests for it, but if its something you need I can shuffle it towards the top of the to do pile. Geremy Condra
From: Gabriel Genellina on 9 Dec 2009 02:09
En Sat, 28 Nov 2009 06:30:44 -0300, Joshua Bronson <jabronson(a)gmail.com> escribi�: > On Nov 27, 9:36 pm, "Gabriel Genellina" <gagsl-py2(a)yahoo.com.ar> > wrote: >> En Fri, 27 Nov 2009 15:12:36 -0300, Francis Carr >> <coldtortuga(a)gmail.com> escribi�: >> >> > After much tinkering, I think I have a simpler solution. Just make >> > the inverse mapping accessible via an attribute, -AND- bind the >> > inverse of -THAT- mapping back to the original. The result is a >> > python dict with NO NEW METHODS except this inverse-mapping >> > attribute. I have posted it on code.activestate.com as <a >> > href="http://code.activestate.com/recipes/576968/">Recipe 576968: >> > Flipdict -- python dict that also maintains a one-to-one inverse >> > mapping</a> > >> Just a couple of comments: >> >> Instead of: >> self._flip = dict.__new__(self.__class__) >> I'd write: >> self._flip = self.__class__() >> unless I'm missing something (but see the next point). > > How would this not cause infinite recursion? That goes under "unless I'm missing something" ;) You're right, it would cause infinite recursion. Not a good idea... >> Also, although Python's GC is able to handle them, I prefer to avoid >> circular references like those between x and x._flip. Making >> self._flip a weak reference (and dereferencing it in the property) >> should be enough. > > If both self._flip and self._flip._flip are weak references, no strong > references to the inverse mapping survive leaving the constructor > scope. Unless I'm missing something, only one of these can be a weak > reference, and then you'd have to do something like this in the > property to prevent "TypeError: FlipDict is not callable": > > @property > def flip(self): > try: > # we're an inverse, self._flip is a weak reference > return self._flip() > except TypeError: > # we're a forward mapping, self._flip is a strong > reference > return self._flip Yes - although I'd explicitely test for a weakref object: def flip(self): _flip = self._flip if isinstance(_filp, weakref.ref): return _flip() return _flip and probably all those internal references to self._flip should become self.flip too; I've not tested the code but I think it *should* work... -- Gabriel Genellina |