Ok I have been a multimedia major for a few years now. I have tried javascript and that was bad, Java is just too difficult, so I joined this mailing list a while back. I have been frustrated because I just don't get entirely how OOProgramming works and how to actually write the stuff correctly. I have a hard time programming and I wish I could be better at knowing at least one language. I need a really good book or something to explain this to me. I am not the best in math On Sep 22, 2007, at 12:46 PM, Kent Johnson wrote:
> Ricardo Aráoz wrote: >> Kent Johnson wrote: > >>> What version of Python are you using? When I try this program it >>> prints >> >> Py 0.9.5 >> Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit >> (Intel)] on win32 >> >> I thought it might be you were trying the class with the list init >> call >> but I tried it and works the same way. >> Was using PyAlaMode, tried it using IDLE and it works like yours, >> probably a bug of PyAlaMode. > > My guess is PyAlaMode is trying to introspect the objects in some way > and that is causing the extra access (to non-existent attributes). > >>> class CallCounter(object): >>> def __init__(self, delegate): >>> self._delegate = delegate >>> self.calls = 0 >>> def __getattr__(self, name): >>> value = getattr(self._delegate, name) >>> if callable(value): >>> self.calls += 1 >>> return value >>> >>> a = CallCounter(list()) >> >> Sadly : >>>>> a = CallCounter(list()) >>>>> a.append(1) >>>>> a.calls >> 2 >>>>> a.append(2) >>>>> a.append(3) >>>>> a.calls >> 5 >>>>> a[3] >> >> Traceback (most recent call last): >> File "<pyshell#15>", line 1, in <module> >> a[3] >> TypeError: 'CallCounter' object is unindexable > > Hmm. The problem is that new-style classes don't look up special > methods > on instances, just in the class itself. > > There is some discussion here, it looks a bit ugly: > http://groups.google.com/group/comp.lang.python/browse_thread/ > thread/c5bb6496970b5c5a?hl=en&tvc=2 > Alex Martelli's second response proposes a solution that overrides > __new__() to create a custom class for each wrapper. > > There might be some help here too, I haven't read it closely: > http://tinyurl.com/25lx5t > > The code works if CallCounter is an old-style class. > > Kent > _______________________________________________ > Tutor maillist - Tutor@python.org > http://mail.python.org/mailman/listinfo/tutor _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
