[Python-Dev] RE: Hot-To Guide for Descriptors (original) (raw)

François Pinard pinard at iro.umontreal.ca
Wed Jan 21 21:33:38 EST 2004

[Jeremy Hylton]

On Wed, 2004-01-21 at 20:24, François Pinard wrote:

> If there is no base class, then "if there's a global variable named > metaclass, it is used." So my guess would be that adding a mere

> metaclass = type

> in global scope for a module would make all classes be "new-style", > without the need to subclass them from object explicitly.

Unless you define a class that inherits from a base class defined in another module.

I thought about this of course. This is no problem in our case, since these other modules will have their `metaclass = type' themselves.

I prefer to inherit from object, because it is more explicit, and avoids possible confusion when some classes have classic bases.

A `metaclass = type' at the beginning of a module is explicit enough to my eyes. If I can demonstrate that this does not harm, it will become a convention here to include this line in each and every module for all in-house projects, and we should be done with classic classes.

Unless we sub-class classic classes from the Python library, I do not know how frequently we do that. By the way :-), I presume there are plans for the Python library to progressively switch to new-style classes whenever possible? If not, should they be?

-- François Pinard http://www.iro.umontreal.ca/~pinard

More information about the Python-Dev mailing list