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"""
These are Python 3.6+-only and keyword-only APIs that call `attr.s` and
`attr.ib` with different default values.
"""
from functools import partial
from attr.exceptions import UnannotatedAttributeError
from . import setters
from ._make import NOTHING, _frozen_setattrs, attrib, attrs
def define(
maybe_cls=None,
*,
these=None,
repr=None,
hash=None,
init=None,
slots=True,
frozen=False,
weakref_slot=True,
str=False,
auto_attribs=None,
kw_only=False,
cache_hash=False,
auto_exc=True,
eq=None,
order=False,
auto_detect=True,
getstate_setstate=None,
on_setattr=None,
field_transformer=None,
):
r"""
The only behavioral differences are the handling of the *auto_attribs*
option:
:param Optional[bool] auto_attribs: If set to `True` or `False`, it behaves
exactly like `attr.s`. If left `None`, `attr.s` will try to guess:
1. If any attributes are annotated and no unannotated `attr.ib`\ s
are found, it assumes *auto_attribs=True*.
2. Otherwise it assumes *auto_attribs=False* and tries to collect
`attr.ib`\ s.
and that mutable classes (``frozen=False``) validate on ``__setattr__``.
.. versionadded:: 20.1.0
"""
def do_it(cls, auto_attribs):
return attrs(
maybe_cls=cls,
these=these,
repr=repr,
hash=hash,
init=init,
slots=slots,
frozen=frozen,
weakref_slot=weakref_slot,
str=str,
auto_attribs=auto_attribs,
kw_only=kw_only,
cache_hash=cache_hash,
auto_exc=auto_exc,
eq=eq,
order=order,
auto_detect=auto_detect,
collect_by_mro=True,
getstate_setstate=getstate_setstate,
on_setattr=on_setattr,
field_transformer=field_transformer,
)
def wrap(cls):
"""
Making this a wrapper ensures this code runs during class creation.
We also ensure that frozen-ness of classes is inherited.
"""
nonlocal frozen, on_setattr
had_on_setattr = on_setattr not in (None, setters.NO_OP)
# By default, mutable classes validate on setattr.
if frozen is False and on_setattr is None:
on_setattr = setters.validate
# However, if we subclass a frozen class, we inherit the immutability
# and disable on_setattr.
for base_cls in cls.__bases__:
if base_cls.__setattr__ is _frozen_setattrs:
if had_on_setattr:
raise ValueError(
"Frozen classes can't use on_setattr "
"(frozen-ness was inherited)."
)
on_setattr = setters.NO_OP
break
if auto_attribs is not None:
return do_it(cls, auto_attribs)
try:
return do_it(cls, True)
except UnannotatedAttributeError:
return do_it(cls, False)
# maybe_cls's type depends on the usage of the decorator. It's a class
# if it's used as `@attrs` but ``None`` if used as `@attrs()`.
if maybe_cls is None:
return wrap
else:
return wrap(maybe_cls)
mutable = define
frozen = partial(define, frozen=True, on_setattr=None)
def field(
*,
default=NOTHING,
validator=None,
repr=True,
hash=None,
init=True,
metadata=None,
converter=None,
factory=None,
kw_only=False,
eq=None,
order=None,
on_setattr=None,
):
"""
Identical to `attr.ib`, except keyword-only and with some arguments
removed.
.. versionadded:: 20.1.0
"""
return attrib(
default=default,
validator=validator,
repr=repr,
hash=hash,
init=init,
metadata=metadata,
converter=converter,
factory=factory,
kw_only=kw_only,
eq=eq,
order=order,
on_setattr=on_setattr,
)
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