[Python-Dev] Submitting PEP 422 (Simple class initialization hook) for pronouncement
Antoine Pitrou
solipsis at pitrou.net
Mon Feb 11 09:02:43 CET 2013
On Sun, 10 Feb 2013 16:27:49 -0500
PJ Eby <pje at telecommunity.com> wrote:
> On Sun, Feb 10, 2013 at 7:32 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:
> > class Example:
> > @classmethod
> > def __init_class__(cls):
>
> Is the @classmethod required? What happens if it's not present?
>
> Second, will type have a default __init_class__? (IMO, it should,
> otherwise it will be impossible to write co-operative __init_class__
> functions.)
>
> Only other comment is that the PEP could use a more concrete use case, e.g.:
>
> class Record:
> __fields = {}
>
> @classmethod
> def __init_class__(cls):
> cls.__fields = dict(cls.__fields) # inherited fields
> cls.__fields.update({attr:val for attr, val in
> cls.__dict__.iteritems() if isinstance(val, Field)})
> super().__init_class__() # be co-operative
>
> # ...other methods that use the __fields attribute
>
> class SomeRecord(Record):
> foo = Field(int)
> bar = Field(str)
>
> Putting something like this early on might help to demonstrate the
> usefulness of the feature on its own merits, independent of the
> porting issue, etc. ;-)
Can you explain what the example does / is supposed to do?
More information about the Python-Dev
mailing list