Bugs item #1297986, was opened at 2005-09-21 19:55 Message generated for change (Comment added) made by birkenfeld You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1297986&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Python Library Group: None Status: Open Resolution: None Priority: 5 Submitted By: ChristianJ (cybb20) Assigned to: Nobody/Anonymous (nobody) Summary: hashable and mutable functions Initial Comment: It is not easy to check if an object is hashable, ie hasattr(list(), '__hash__') -> True try: hash(list()) except TypeError: pass seems to be a possible way to see if an object is hashable, however it is not satisfiable that this information needs to be retrieved by using exception handling. My proposal: There should be a hashable(obj) function returning a bool object and additionally it would be nice to have something like ismutable(obj) function, possibly as built-in functions. Reason: callable() is a built-in function and returns information about an object whether it's callable or not, that is a basic info about this object. If an object is hashable or mutable is a state of an object that is also very important to know. ---------------------------------------------------------------------- >Comment By: Reinhold Birkenfeld (birkenfeld) Date: 2005-09-22 08:27 Message: Logged In: YES user_id=1188172 > try: hash(list()) > except TypeError: pass > > seems to be a possible way to see if an object is > hashable, however it is not satisfiable that this > information needs to be retrieved by using exception > handling. Why? > My proposal: > There should be a hashable(obj) function returning a > bool object and additionally it would be nice to have > something like ismutable(obj) function, possibly as > built-in functions. How should "ismutable" be implemented? > Reason: > callable() is a built-in function and returns > information about an object whether it's callable or > not, that is a basic info about this object. > If an object is hashable or mutable is a state of an > object that is also very important to know. It's easier to ask for forgiveness than permission. Even callable() has been called a mistake. Just call it and see where you come. So, -1. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1297986&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
