Christian Heimes added the comment: All major Python implementation have a mutual agreement that callable() just checks for a __call__ member on the type. You also haven't shown that this behavior violates the documentation and language spec. The check for existence of __call__ on the type is well in the range of expected behavior. I as well as other core devs had the same gut feeling.
Finally your suggestion makes the implementation of callable() more complex and much, much slower. Right now and for more than a decade it is a simple, fast and straight forward code path for new style classes. It just requires two pointer derefs and one comparison to NULL. I'm still -1 on the change. If you want to go forth with your request then you must write a PEP and convince all implementors of Python implementations to change the current way callable() and other protocols like iter work. $ python2.7 Python 2.7.8 (default, Nov 10 2014, 08:19:18) [GCC 4.9.2 20141101 (Red Hat 4.9.2-1)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> class A(object): ... @property ... def __call__(self): ... raise AttributeError ... >>> a = A() >>> print(callable(a)) True >>> a() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 4, in __call__ AttributeError $ jython Jython 2.7b3+ (, Nov 3 2014, 11:02:14) [OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.8.0_40 Type "help", "copyright", "credits" or "license" for more information. >>> class A(object): ... @property ... def __call__(self): ... raise AttributeError ... >>> a = A() >>> print(callable(a)) True >>> a() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 4, in __call__ AttributeError $ pypy Python 2.7.8 (a980ebb26592ed26706cd33a4e05eb45b5d3ea09, Sep 24 2014, 07:41:52) [PyPy 2.4.0 with GCC 4.9.1 20140912 (Red Hat 4.9.1-9)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>>> class A(object): .... @property .... def __call__(self): .... raise AttributeError .... >>>> a = A() >>>> print(callable(a)) True >>>> a() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 4, in __call__ AttributeError ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue23990> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
