אורי wrote:
> Why does this not work:
>
> class User(ValidateUserPasswordMixin, PermissionsMixin, Entity,
> AbstractBaseUser):
> GENDER_VALID_VALUES = [choice[0] for choice in GENDER_CHOICES]
> GENDERS_DICT = {GENDER_FEMALE: GENDER_FEMALE_STRING, GENDER_MALE:
> ALL_GENDERS = [GENDERS_DICT[gender] for gender in GENDER_VALID_VALUES]
>
> (it throws an exception: `NameError: name 'GENDERS_DICT' is not defined`)
The list comprehension in Python 3 works like a generator generator
expression:
https://www.python.org/dev/peps/pep-0289/?modTest=#the-details
In your case GENDER_VALID_VALUES is looked up in the class, and GENDERS_DICT
is looked up in the function synthesized from the list comprehension.
As with methods this function only sees the local and the global namespace,
but not the class namespace.
I realise that this is a long-winded way of saying "it is like it is",
but maybe it helps you understand what works and what doesn't.
This would work for example (not recommended for actual use):
ALL_GENDERS = [
GENDERS_DICT[gender] for gender, GENDERS_DICT in
zip(GENDER_VALID_VALUES, itertools.repeat(GENDERS_DICT))
]
> But this works:
> User.ALL_GENDERS = [User.GENDERS_DICT[gender] for gender in
> User.GENDER_VALID_VALUES]
User exists in the global namespace, and has both attributes, so no
surprises here.
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