On Sat, Jun 22, 2013 at 11:23 PM, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > On Sat, 22 Jun 2013 22:27:10 -0600, Ian Kelly wrote: >> I actually consider that an up side. Sure it's inconvenient that you >> can't delegate all such methods at once just by overriding >> __getattribute__, but it would be more troublesome to *accidentally* >> implement such methods because you implemented __getattribute__. > > It's hard to see a case where that would be a bad thing. > > 1) If the proxied object doesn't include __dunder__ methods, then the > proxy will just end up up calling the default object dunder methods, > exactly as if they weren't proxied. > > 2) If the proxied object does include dunders, then you generally want > the proxy to call them, with perhaps one or two exceptions, which need to > be overridden regardless of whether they are dunders or not.
Proxying objects is not the only use of __getattribute__. >> And >> then there are methods that really should not be delegated in the first >> place, like __del__. > > If you're using __del__, you're probably doing something wrong :-) > > I suppose that __del__ is a good counter-example, but (1) hardly any > classes use __del__, and (2) for those that do, it's *way* simpler to > manually override __del__ in the proxy than to manually delegate every > dunder method you care about. There are typically a lot of dunder methods > you care about. If you manually override __del__ in the proxy, then as far as the garbage collector is concerned, your proxy object has a __del__ method (even if it does nothing), and so it will be treated differently from an object without a __del__ method. > It is not the case that dunder methods cannot be automatically proxied > because somebody deliberately designed Python to work that way. It's an > accidental side-effect of the way new-style classes resolve method calls, > due to decisions made for other reasons having nothing to do with > delegation. Can you elaborate or provide a link? I'm curious to know what other reason there could be for magic methods to behave differently from normal methods in this regard. -- http://mail.python.org/mailman/listinfo/python-list
