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

Guido van Rossum guido at python.org
Wed Jan 21 15:34:46 EST 2004

François Pinard writes: > Would it be more precise to state: > "... new style objects or classes (those for which the meta-class is a > subtype of type')"? Being sub-classed from object or type is just a_ _> way, among others, for identifying type' as the meta-class; but being > sub-classed from object is not really required.

Raymond Hettinger responds: > Nope, new-style is taken to mean objects/classes inheriting from > object/type. Meta-class objects are neither new-style nor old-style. > While there is room to argue with this arbitrary distinction, it is > consistent with Guido's essay and especially relevant to my article > because most of the rules don't necessarily apply when meta-classes > are used. This is because the machinery for descriptors is > embedded in type.getattribute and object.getattribute. > Override or fail to inherit either of these and all bets are off.

Michael Chermside

Really? I realize the utility of having a term for objects-with-a- meta-type-of-type, but I had always understood "new-style" to mean things-that-are-not-old-style-classes. I can live with either definition, but the Python community should make sure that we use the term "new-style class" in a consistent fashion.

Did everyone else agree with Raymond so François and I are the odd men out, or is there a larger confusion over how we use the term?

I'm with Raymond. Metaclasses that don't derive from 'type' can create objects that are neither fish nor flesh.

--Guido van Rossum (home page: http://www.python.org/~guido/)

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