But on calling `type` in this way, you are passing the namespace as a ready object, as the 3rdy parameter - what would `__prepare__` even do, besides print it's been called?
For sometime (maybe Python 3.3, I forgot), some helper callables where added to the `types` module to allow one to have more freedom in imperatively created classes: ````python In [20]: types.prepare_class? Signature: types.prepare_class(name, bases=(), kwds=None) Docstring: Call the __prepare__ method of the appropriate metaclass. Returns (metaclass, namespace, kwds) as a 3-tuple *metaclass* is the appropriate metaclass *namespace* is the prepared class namespace *kwds* is an updated copy of the passed in kwds argument with any 'metaclass' entry removed. If no kwds argument is passed in, this will be an empty dict. File: ~/projetos/terminedia/env/lib64/python3.7/types.py Type: function In [21]: types.new_class? Signature: types.new_class(name, bases=(), kwds=None, exec_body=None) Docstring: Create a class object dynamically using the appropriate metaclass. File: ~/projetos/terminedia/env/lib64/python3.7/types.py Type: function In [22]: types.resolve_bases? Signature: types.resolve_bases(bases) Docstring: Resolve MRO entries dynamically as specified by PEP 560. File: ~/projetos/terminedia/env/lib64/python3.7/types.py Type: function ``` On Mon, 1 Jun 2020 at 16:28, Ethan Furman <[email protected]> wrote: > > From stackoverflow [1] > > # metaprepare.py > class Meta1(type): > @classmethod > def __prepare__(mcs, name, bases): > print('call prepare') > return {} > def __new__(mcs, name, bases, parameters): > return super().__new__(mcs, name, bases, parameters) > > class A(metaclass=Meta1): > pass > > type('C', (A, ), {}) > > output is: > > call prepare > > (just the once, not twice) > > The behavior of `type()` not calling `__prepare__()` has been constant since > 3.3. > > Is it a bug? > > > -- > ~Ethan~ > > > [1] https://stackoverflow.com/q/62128254/208880 > _______________________________________________ > Python-Dev mailing list -- [email protected] > To unsubscribe send an email to [email protected] > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/[email protected]/message/CQTD7WFOIDBF5PSD77AALBTWJQ67UPM5/ > Code of Conduct: http://python.org/psf/codeofconduct/ _______________________________________________ Python-Dev mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/[email protected]/message/IPBWREEI6JYGWROTSXGHBWLG53Q4A23A/ Code of Conduct: http://python.org/psf/codeofconduct/