# SPDX-License-Identifier: MIT
"""
These are keyword-only APIs that call `attr.s` and `attr.ib` with different
default values.
"""
from functools import partial
from . import setters
from ._funcs import asdict as _asdict
from ._funcs import astuple as _astuple
from ._make import (
NOTHING,
_frozen_setattrs,
_ng_default_on_setattr,
attrib,
attrs,
)
from .exceptions import UnannotatedAttributeError
[docs]
def define(
maybe_cls=None,
*,
these=None,
repr=None,
unsafe_hash=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,
match_args=True,
):
r"""
Define an *attrs* class.
Differences to the classic `attr.s` that it uses underneath:
- Automatically detect whether or not *auto_attribs* should be `True` (c.f.
*auto_attribs* parameter).
- Converters and validators run when attributes are set by default -- if
*frozen* is `False`.
- *slots=True*
.. caution::
Usually this has only upsides and few visible effects in everyday
programming. But it *can* lead to some surprising behaviors, so please
make sure to read :term:`slotted classes`.
- *auto_exc=True*
- *auto_detect=True*
- *order=False*
- Some options that were only relevant on Python 2 or were kept around for
backwards-compatibility have been removed.
Please note that these are all defaults and you can change them as you
wish.
: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 `attrs.fields`\ s
are found, it assumes *auto_attribs=True*.
2. Otherwise it assumes *auto_attribs=False* and tries to collect
`attrs.fields`\ s.
For now, please refer to `attr.s` for the rest of the parameters.
.. versionadded:: 20.1.0
.. versionchanged:: 21.3.0 Converters are also run ``on_setattr``.
.. versionadded:: 22.2.0
*unsafe_hash* as an alias for *hash* (for :pep:`681` compliance).
"""
def do_it(cls, auto_attribs):
return attrs(
maybe_cls=cls,
these=these,
repr=repr,
hash=hash,
unsafe_hash=unsafe_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,
match_args=match_args,
)
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 convert & validate on setattr.
if frozen is False and on_setattr is None:
on_setattr = _ng_default_on_setattr
# 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:
msg = "Frozen classes can't use on_setattr (frozen-ness was inherited)."
raise ValueError(msg)
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
return wrap(maybe_cls)
mutable = define
frozen = partial(define, frozen=True, on_setattr=None)
[docs]
def field(
*,
default=NOTHING,
validator=None,
repr=True,
hash=None,
init=True,
metadata=None,
type=None,
converter=None,
factory=None,
kw_only=False,
eq=None,
order=None,
on_setattr=None,
alias=None,
):
"""
Identical to `attr.ib`, except keyword-only and with some arguments
removed.
.. versionadded:: 23.1.0
The *type* parameter has been re-added; mostly for `attrs.make_class`.
Please note that type checkers ignore this metadata.
.. versionadded:: 20.1.0
"""
return attrib(
default=default,
validator=validator,
repr=repr,
hash=hash,
init=init,
metadata=metadata,
type=type,
converter=converter,
factory=factory,
kw_only=kw_only,
eq=eq,
order=order,
on_setattr=on_setattr,
alias=alias,
)
[docs]
def asdict(inst, *, recurse=True, filter=None, value_serializer=None):
"""
Same as `attr.asdict`, except that collections types are always retained
and dict is always used as *dict_factory*.
.. versionadded:: 21.3.0
"""
return _asdict(
inst=inst,
recurse=recurse,
filter=filter,
value_serializer=value_serializer,
retain_collection_types=True,
)
[docs]
def astuple(inst, *, recurse=True, filter=None):
"""
Same as `attr.astuple`, except that collections types are always retained
and `tuple` is always used as the *tuple_factory*.
.. versionadded:: 21.3.0
"""
return _astuple(
inst=inst, recurse=recurse, filter=filter, retain_collection_types=True
)
