Thanks Daniel, I found my answer here (using your link): https://docs.python.org/3/reference/datamodel.html#preparing-the-class-namespace
""" When a new class is created by type.__new__, the object provided as the namespace parameter is copied to a new ordered mapping and the original object is discarded. """ Therefore the answer seems to be that https://www.python.org/dev/peps/pep-3115/ needs to be updated & fixed. Replace the following: """ def __new__(cls, name, bases, classdict): # Note that we replace the classdict with a regular # dict before passing it to the superclass, so that we # don't continue to record member names after the class # has been created. result = type.__new__(cls, name, bases, dict(classdict)) result.member_names = classdict.member_names return result """ With: """ def __new__(cls, name, bases, classdict): result = type.__new__(cls, name, bases, classdict) result.member_names = classdict.member_names return result """ Removing the incorrect comments & the copying of `classdict` I will go file a bug report to that effect. Thanks, Joy Diamond. On Sat, Nov 3, 2018 at 7:55 PM Daniel Moisset <dfmois...@gmail.com> wrote: > If I understood correctly what you want, it's possible with a metaclass. > Check the __prepare__ method at > https://docs.python.org/3/reference/datamodel.html#preparing-the-class-namespace > and Pep 3115 > > On Sat, 3 Nov 2018, 20:55 Joy Diamond <python....@gmail.com wrote: > >> Team, >> >> Are we supposed to be able to have our own class dictionary in python 3? >> >> If we currently cannot -- do we want to be able to? >> >> That we can have out own class dictionary in python 3 is strongly implied >> in the following at https://www.python.org/dev/peps/pep-3115/ where it >> says: >> >> """ >> >> # The metaclass invocation >> def __new__(cls, name, bases, classdict): >> # Note that we replace the classdict with a regular >> # dict before passing it to the superclass, so that we >> # don't continue to record member names after the class >> # has been created. >> result = type.__new__(cls, name, bases, dict(classdict)) >> result.member_names = classdict.member_names >> return result >> >> """ >> >> I don't understand this. As far as I can tell, no matter what class >> dictionary you pass into `type.__new__` it creates a copy of it. >> >> Am I missing something? Is this supposed to work? Is the documentation >> wrong? >> >> Thanks, >> >> Joy Diamond. >> >> Program that shows that the class dictionary created is not what we pass >> in --- Shows the actual symbol table is `dict` not `SymbolTable` >> >> class SymbolTable(dict): >> pass >> >> members = SymbolTable(a = 1) >> >> X = type('X', ((object,)), members) >> >> members['b'] = 2 >> >> print('X.a: {}'.format(X.a)) >> >> try: >> print('X.b: {}'.format(X.b)) >> except AttributeError as e: >> print('X.b: does not exist') >> >> # >> # Get the actual symbol table of `X`, bypassing the mapping proxy. >> # >> X__symbol_table = __import__('gc').get_referents(X.__dict__)[0] >> >> print('The type of the actual symbol table of X is: {} with keys: >> {}'.format( >> type(X__symbol_table), >> X__symbol_table.keys())) >> >> >> # Prints out >> # X.a: 1 >> # X.b: does not exist >> # The type of the actual symbol table of X is: <class 'dict'> with keys: >> dict_keys(['a', '__module__', '__dict__', '__weakref__', '__doc__']) >> >> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> >> Virus-free. >> www.avast.com >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> >> <#m_3863327966708087084_m_7370047320667964513_m_603818574152564677_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >> _______________________________________________ >> Python-ideas mailing list >> Python-ideas@python.org >> https://mail.python.org/mailman/listinfo/python-ideas >> Code of Conduct: http://python.org/psf/codeofconduct/ >> >
_______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
