Nick Coghlan wrote:
On Thu, May 10, 2012 at 10:03 AM, Greg Ewing
<greg.ew...@canterbury.ac.nz> wrote:
Python is not Java -- we have modules. Something should
only go in a class namespace if it somehow relates to
that particular class, and other classes could might
implement it differently. That's not the case with
build_class().
+1
Not true - you *will* get a type instance out of any sane call to
type.define(). Technically, you could probably declare your metaclass
such that you get a non-type object instead (just as you can with a
class definition), but that means you're really just using an insanely
convoluted way to make an ordinary function call. If you didn't want
to invoke the full PEP 3115 find metaclass/prepare namespace/execute
body/call metaclass dance, why would you be calling type.define
instead of just calling the metaclass directly?
By attaching the 'define' object to type, then the descriptor protocol
causes problems if 'define' is a desriptor since type is its own
metaclass. If it were a builtin-function, then there would be no problem.
A module-level builtin-function is more likely to be correct and seems
to me to be more Pythonic. Not that I'm a good judge of Pythonicness :)
Finally, could you remind me how the proposed type.define differs from
builtins.__build_class__?
I can't see any difference (apart from parameter ordering and the extra
name parameter in builtins.__build_class__).
Cheers,
Mark.
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