Nathan Dunn writes: > > * the mapping protocol covers more than just __getitem__ > > __setitem__(self, key, value) could be def self[key] = value > likewise > __delitem__(self, key) def del self[key]: > __iter__(self) iter(self) > __len__(self) len(self)
The template used by last two (BTW, shouldn't they be "def iter(self)" and "def len(self)"?) seems like a really bad idea to me. This would imply that any class that defines such methods in some arbitrary fashion will appear to participate in the corresponding protocol although it doesn't. That seems likely to result in bugs, that might be hard to diagnose (haven't thought about how hard that might be, though). It would require the programmer to know about all such protocols when designing a public API, while with the dunder convention, you only need to find out whether the dunders you want to use for your new protocol are already in use somewhere, and programmers who aren't designing protocols don't need to know about them at all. It would also require a modification to the compiler for every new protocol. I personally don't see that the other syntaxes are helpful, either, but that's a matter of opinion and I'd be interested to hear about experience with teaching languages that implement such "method definitions look like invocation syntax". Regards, _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
