Steven D'Aprano wrote: > On Mon, 19 Mar 2007 19:48:37 +1100, Ben Finney wrote: > >> It's also best to inherit every class from another class, leading to a >> single hierarchy for all classes and types. 'object' is the one to >> choose if you don't want the behaviour of any other class. > > What's wrong with old-style classes? > > On the plus side: > > - Why inherit from something if you don't need to? > > - Less typing. > > - Attribute-lookup is much faster, perhaps as much as twice as fast. > http://www.python.org/~jeremy/weblog/030506.html > > - Documentation on old style classes is more extensive. > > - You can't use new style classes for exceptions. > In 2.5 exceptions are new-style objects, thanks to Brett Cannon's PyCon work from 2006:
Python 2.4.3 (#69, Mar 29 2006, 17:35:34) [MSC v.1310 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information. Started with C:/Steve/.pythonrc >>> Exception <class exceptions.Exception at 0x00964510> >>> Python 2.5b2 (trunk:50713, Jul 19 2006, 16:04:09) [GCC 3.4.4 (cygming special) (gdc 0.12, using dmd 0.125)] on cygwin Type "help", "copyright", "credits" or "license" for more information. Started with C:/Steve/.pythonrc >>> Exception <type 'exceptions.Exception'> >>> > > > On the minus side: > > - Properties don't work as you expect them too. > > - Slots don't work at all. > > > In other words, the only reason why you HAVE to use a new style class is > that you need properties or __slots__. You might WANT to use a new style > class to inherit from built-in types. Otherwise, the choice between old > and new is not very important. > > > Most of the documentation on old-style classes, of course, applies to new-style classes too. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://del.icio.us/steve.holden Recent Ramblings http://holdenweb.blogspot.com -- http://mail.python.org/mailman/listinfo/python-list
