New submission from Larry Hastings: I found something curious while experimenting with types tonight.
Everybody knows, if you access a descriptor in a class through the normal attribute-getting methods, you actually get the result of calling its '__get__' method. If you want to get your hands on the descriptor itself, you can be sneaky and pull it out through the class's __dict__. I did an experiment tonight, accessing a bunch of methods in a bunch of different ways. The methods I tried were * an instance method, * a class method, and * a static method. I accessed them * as an instance attribute, * as a class attribute, and * through the class __dict__. And for each of the above, I tried * one user method and * one built-in method. That's a total of eighteen methods tried (3x3x2). For each one, I printed out whether or not it was callable. I found the results startling: fifteen were, but three (!) were not. All three that weren't were accessed through the class dict. They were: * Class method, from builtin class ( dict.__dict__['fromkeys'] ) * Static method, from user class * Static method, from builtin class ( str.__dict__['maketrans'] ) I find it strange that the static method descriptors aren't callable. I find it *even stranger* that *one* of the class method descriptors isn't callable, but the other one is. I guess a foolish consistency is the hobgoblin of my small mind, but... shouldn't all eighteen of these objects be callable? Attached is the test harness I wrote. (p.s. I attached you guys as nosy because I thought you might be interested.) ---------- components: Interpreter Core files: curious.py messages: 208524 nosy: arigo, larry, ncoghlan, pitrou priority: low severity: normal stage: needs patch status: open title: Class method descriptors are different between builtin and user classes type: behavior versions: Python 3.4 Added file: http://bugs.python.org/file33559/curious.py _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue20309> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
