WANG Cong a écrit : > On 06/25/10 15:34, Bruno Desthuilliers > <bruno.42.desthuilli...@websiteburo.invalid> wrote: > >> WANG Cong a écrit : >>> Hi, list! >>> >>> I have a doubt about the design of dynamic attribute creation by >>> assignments in Python. >>> >>> As we know, in Python, we are able to create a new attribute of >>> a class dynamically by an assignment: >>> >>>>>> class test: pass >>> ... >>>>>> test.a = "hello" >>>>>> test.a >>> 'hello' >>> >>> However, I still don't get the points why Python designs it like this. >>> >>> My points are: >>> >> (snip) >> >> Python's classes are plain objects, and like any other object are >> created at runtime. Having to special-case them would break the >> simplicity and uniformity of Python for no good reason. Just like >> there's no good reason to make setattr() working differently for class >> and non-class objects. >> > > For implementaiton, perhaps, but not for the language design, how could > a language design be perfect if we can use setattr() like assignments > while use other things, e.g. delattr(), not? Is there any way to express > delattr() as simple as expressing setattr() with assignments? I doubt...
cf Ethan's answer on this. > Using assignments to create an attribute hides metaprogramming > while using delattr() exposes it. Once again : in Python, none of this is "metaprogramming" - just plain ordinary programming. So called "metaprogramming" is just an artefact of static languages where datastructures are created at compile time. -- http://mail.python.org/mailman/listinfo/python-list
