On Thu, 07 Jun 2012 07:00:29 -0700, Larry Hastings <la...@hastings.org> wrote: > On 06/06/2012 11:56 PM, Nick Coghlan wrote: > > I'd say return a copy in the first case to be safe against accidental > > modification. If someone actually wants in-place modification, they > > can access __signature__ directly. > > I really don't understand this anxiety about mutable Signature objects. > Can you give a plausible example of "accidental modification" of a > Signature object? I for one--as clumsy as I am--cannot recall ever > "accidentally" modifying an object.
Maybe it would make more sense if you read that as "naively" rather than "accidentally"? In the 3.3 email extension I made a similar decision, although there I went even further and made the objects read only. My logic for doing this is that a naive user would...naively...try to set the attributes and expect the object they got it from to change, but that object (a string subclass) is inherently read-only. I am thinking that in fact we may ultimately want to return copies of these objects that are mutable, because that might be useful, but I'm starting with read-only because it is easy to make them mutable later but pretty much impossible (backward compatibility wise) to make them immutable if they start mutable. I see the signature object as a very parallel case to this, except that it is already obvious that having them be a mutable copy is useful. --David _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
