523 lines
17 KiB
Python
523 lines
17 KiB
Python
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# SPDX-License-Identifier: MIT
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import copy
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from ._compat import PY_3_9_PLUS, get_generic_base
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from ._make import _OBJ_SETATTR, NOTHING, fields
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from .exceptions import AttrsAttributeNotFoundError
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def asdict(
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inst,
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recurse=True,
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filter=None,
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dict_factory=dict,
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retain_collection_types=False,
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value_serializer=None,
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):
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"""
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Return the *attrs* attribute values of *inst* as a dict.
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Optionally recurse into other *attrs*-decorated classes.
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Args:
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inst: Instance of an *attrs*-decorated class.
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recurse (bool): Recurse into classes that are also *attrs*-decorated.
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filter (~typing.Callable):
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A callable whose return code determines whether an attribute or
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element is included (`True`) or dropped (`False`). Is called with
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the `attrs.Attribute` as the first argument and the value as the
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second argument.
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dict_factory (~typing.Callable):
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A callable to produce dictionaries from. For example, to produce
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ordered dictionaries instead of normal Python dictionaries, pass in
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``collections.OrderedDict``.
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retain_collection_types (bool):
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Do not convert to `list` when encountering an attribute whose type
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is `tuple` or `set`. Only meaningful if *recurse* is `True`.
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value_serializer (typing.Callable | None):
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A hook that is called for every attribute or dict key/value. It
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receives the current instance, field and value and must return the
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(updated) value. The hook is run *after* the optional *filter* has
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been applied.
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Returns:
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Return type of *dict_factory*.
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Raises:
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attrs.exceptions.NotAnAttrsClassError:
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If *cls* is not an *attrs* class.
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.. versionadded:: 16.0.0 *dict_factory*
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.. versionadded:: 16.1.0 *retain_collection_types*
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.. versionadded:: 20.3.0 *value_serializer*
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.. versionadded:: 21.3.0
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If a dict has a collection for a key, it is serialized as a tuple.
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"""
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attrs = fields(inst.__class__)
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rv = dict_factory()
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for a in attrs:
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v = getattr(inst, a.name)
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if filter is not None and not filter(a, v):
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continue
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if value_serializer is not None:
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v = value_serializer(inst, a, v)
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if recurse is True:
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if has(v.__class__):
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rv[a.name] = asdict(
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v,
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recurse=True,
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filter=filter,
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dict_factory=dict_factory,
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retain_collection_types=retain_collection_types,
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value_serializer=value_serializer,
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)
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elif isinstance(v, (tuple, list, set, frozenset)):
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cf = v.__class__ if retain_collection_types is True else list
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items = [
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_asdict_anything(
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i,
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is_key=False,
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filter=filter,
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dict_factory=dict_factory,
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retain_collection_types=retain_collection_types,
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value_serializer=value_serializer,
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)
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for i in v
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]
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try:
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rv[a.name] = cf(items)
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except TypeError:
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if not issubclass(cf, tuple):
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raise
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# Workaround for TypeError: cf.__new__() missing 1 required
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# positional argument (which appears, for a namedturle)
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rv[a.name] = cf(*items)
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elif isinstance(v, dict):
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df = dict_factory
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rv[a.name] = df(
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(
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_asdict_anything(
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kk,
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is_key=True,
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filter=filter,
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dict_factory=df,
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retain_collection_types=retain_collection_types,
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value_serializer=value_serializer,
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),
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_asdict_anything(
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vv,
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is_key=False,
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filter=filter,
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dict_factory=df,
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retain_collection_types=retain_collection_types,
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value_serializer=value_serializer,
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),
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)
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for kk, vv in v.items()
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)
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else:
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rv[a.name] = v
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else:
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rv[a.name] = v
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return rv
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def _asdict_anything(
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val,
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is_key,
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filter,
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dict_factory,
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retain_collection_types,
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value_serializer,
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):
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"""
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``asdict`` only works on attrs instances, this works on anything.
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"""
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if getattr(val.__class__, "__attrs_attrs__", None) is not None:
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# Attrs class.
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rv = asdict(
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val,
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recurse=True,
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filter=filter,
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dict_factory=dict_factory,
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retain_collection_types=retain_collection_types,
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value_serializer=value_serializer,
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)
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elif isinstance(val, (tuple, list, set, frozenset)):
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if retain_collection_types is True:
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cf = val.__class__
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elif is_key:
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cf = tuple
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else:
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cf = list
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rv = cf(
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[
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_asdict_anything(
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i,
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is_key=False,
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filter=filter,
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dict_factory=dict_factory,
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retain_collection_types=retain_collection_types,
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value_serializer=value_serializer,
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)
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for i in val
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]
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)
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elif isinstance(val, dict):
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df = dict_factory
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rv = df(
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(
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_asdict_anything(
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kk,
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is_key=True,
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filter=filter,
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dict_factory=df,
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retain_collection_types=retain_collection_types,
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value_serializer=value_serializer,
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),
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_asdict_anything(
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vv,
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is_key=False,
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filter=filter,
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dict_factory=df,
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retain_collection_types=retain_collection_types,
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value_serializer=value_serializer,
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),
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)
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for kk, vv in val.items()
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)
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else:
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rv = val
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if value_serializer is not None:
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rv = value_serializer(None, None, rv)
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return rv
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def astuple(
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inst,
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recurse=True,
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filter=None,
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tuple_factory=tuple,
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retain_collection_types=False,
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):
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"""
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Return the *attrs* attribute values of *inst* as a tuple.
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Optionally recurse into other *attrs*-decorated classes.
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Args:
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inst: Instance of an *attrs*-decorated class.
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recurse (bool):
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Recurse into classes that are also *attrs*-decorated.
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filter (~typing.Callable):
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A callable whose return code determines whether an attribute or
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element is included (`True`) or dropped (`False`). Is called with
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the `attrs.Attribute` as the first argument and the value as the
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second argument.
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tuple_factory (~typing.Callable):
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A callable to produce tuples from. For example, to produce lists
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instead of tuples.
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retain_collection_types (bool):
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Do not convert to `list` or `dict` when encountering an attribute
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which type is `tuple`, `dict` or `set`. Only meaningful if
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*recurse* is `True`.
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Returns:
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Return type of *tuple_factory*
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Raises:
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attrs.exceptions.NotAnAttrsClassError:
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If *cls* is not an *attrs* class.
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.. versionadded:: 16.2.0
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"""
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attrs = fields(inst.__class__)
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rv = []
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retain = retain_collection_types # Very long. :/
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for a in attrs:
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v = getattr(inst, a.name)
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if filter is not None and not filter(a, v):
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continue
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if recurse is True:
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if has(v.__class__):
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rv.append(
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astuple(
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v,
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recurse=True,
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filter=filter,
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tuple_factory=tuple_factory,
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retain_collection_types=retain,
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)
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)
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elif isinstance(v, (tuple, list, set, frozenset)):
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cf = v.__class__ if retain is True else list
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items = [
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(
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astuple(
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j,
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recurse=True,
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filter=filter,
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tuple_factory=tuple_factory,
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retain_collection_types=retain,
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)
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if has(j.__class__)
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else j
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)
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for j in v
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]
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try:
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rv.append(cf(items))
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except TypeError:
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if not issubclass(cf, tuple):
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raise
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# Workaround for TypeError: cf.__new__() missing 1 required
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# positional argument (which appears, for a namedturle)
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rv.append(cf(*items))
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elif isinstance(v, dict):
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df = v.__class__ if retain is True else dict
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rv.append(
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df(
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(
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(
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astuple(
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kk,
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tuple_factory=tuple_factory,
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retain_collection_types=retain,
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)
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if has(kk.__class__)
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else kk
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),
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(
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astuple(
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vv,
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tuple_factory=tuple_factory,
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retain_collection_types=retain,
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)
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if has(vv.__class__)
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else vv
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),
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)
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for kk, vv in v.items()
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)
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)
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else:
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rv.append(v)
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else:
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rv.append(v)
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return rv if tuple_factory is list else tuple_factory(rv)
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def has(cls):
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"""
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Check whether *cls* is a class with *attrs* attributes.
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Args:
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cls (type): Class to introspect.
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Raises:
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TypeError: If *cls* is not a class.
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Returns:
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bool:
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"""
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attrs = getattr(cls, "__attrs_attrs__", None)
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if attrs is not None:
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return True
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# No attrs, maybe it's a specialized generic (A[str])?
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generic_base = get_generic_base(cls)
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if generic_base is not None:
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generic_attrs = getattr(generic_base, "__attrs_attrs__", None)
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if generic_attrs is not None:
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# Stick it on here for speed next time.
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cls.__attrs_attrs__ = generic_attrs
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return generic_attrs is not None
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return False
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def assoc(inst, **changes):
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"""
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Copy *inst* and apply *changes*.
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This is different from `evolve` that applies the changes to the arguments
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that create the new instance.
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`evolve`'s behavior is preferable, but there are `edge cases`_ where it
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doesn't work. Therefore `assoc` is deprecated, but will not be removed.
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.. _`edge cases`: https://github.com/python-attrs/attrs/issues/251
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Args:
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inst: Instance of a class with *attrs* attributes.
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changes: Keyword changes in the new copy.
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Returns:
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A copy of inst with *changes* incorporated.
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Raises:
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attrs.exceptions.AttrsAttributeNotFoundError:
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If *attr_name* couldn't be found on *cls*.
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attrs.exceptions.NotAnAttrsClassError:
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If *cls* is not an *attrs* class.
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.. deprecated:: 17.1.0
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Use `attrs.evolve` instead if you can. This function will not be
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removed du to the slightly different approach compared to
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`attrs.evolve`, though.
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"""
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new = copy.copy(inst)
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attrs = fields(inst.__class__)
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for k, v in changes.items():
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a = getattr(attrs, k, NOTHING)
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if a is NOTHING:
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msg = f"{k} is not an attrs attribute on {new.__class__}."
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raise AttrsAttributeNotFoundError(msg)
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_OBJ_SETATTR(new, k, v)
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return new
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def evolve(*args, **changes):
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"""
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Create a new instance, based on the first positional argument with
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*changes* applied.
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Args:
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inst:
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Instance of a class with *attrs* attributes. *inst* must be passed
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as a positional argument.
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changes:
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Keyword changes in the new copy.
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|
|
Returns:
|
||
|
|
A copy of inst with *changes* incorporated.
|
||
|
|
|
||
|
|
Raises:
|
||
|
|
TypeError:
|
||
|
|
If *attr_name* couldn't be found in the class ``__init__``.
|
||
|
|
|
||
|
|
attrs.exceptions.NotAnAttrsClassError:
|
||
|
|
If *cls* is not an *attrs* class.
|
||
|
|
|
||
|
|
.. versionadded:: 17.1.0
|
||
|
|
.. deprecated:: 23.1.0
|
||
|
|
It is now deprecated to pass the instance using the keyword argument
|
||
|
|
*inst*. It will raise a warning until at least April 2024, after which
|
||
|
|
it will become an error. Always pass the instance as a positional
|
||
|
|
argument.
|
||
|
|
.. versionchanged:: 24.1.0
|
||
|
|
*inst* can't be passed as a keyword argument anymore.
|
||
|
|
"""
|
||
|
|
try:
|
||
|
|
(inst,) = args
|
||
|
|
except ValueError:
|
||
|
|
msg = (
|
||
|
|
f"evolve() takes 1 positional argument, but {len(args)} were given"
|
||
|
|
)
|
||
|
|
raise TypeError(msg) from None
|
||
|
|
|
||
|
|
cls = inst.__class__
|
||
|
|
attrs = fields(cls)
|
||
|
|
for a in attrs:
|
||
|
|
if not a.init:
|
||
|
|
continue
|
||
|
|
attr_name = a.name # To deal with private attributes.
|
||
|
|
init_name = a.alias
|
||
|
|
if init_name not in changes:
|
||
|
|
changes[init_name] = getattr(inst, attr_name)
|
||
|
|
|
||
|
|
return cls(**changes)
|
||
|
|
|
||
|
|
|
||
|
|
def resolve_types(
|
||
|
|
cls, globalns=None, localns=None, attribs=None, include_extras=True
|
||
|
|
):
|
||
|
|
"""
|
||
|
|
Resolve any strings and forward annotations in type annotations.
|
||
|
|
|
||
|
|
This is only required if you need concrete types in :class:`Attribute`'s
|
||
|
|
*type* field. In other words, you don't need to resolve your types if you
|
||
|
|
only use them for static type checking.
|
||
|
|
|
||
|
|
With no arguments, names will be looked up in the module in which the class
|
||
|
|
was created. If this is not what you want, for example, if the name only
|
||
|
|
exists inside a method, you may pass *globalns* or *localns* to specify
|
||
|
|
other dictionaries in which to look up these names. See the docs of
|
||
|
|
`typing.get_type_hints` for more details.
|
||
|
|
|
||
|
|
Args:
|
||
|
|
cls (type): Class to resolve.
|
||
|
|
|
||
|
|
globalns (dict | None): Dictionary containing global variables.
|
||
|
|
|
||
|
|
localns (dict | None): Dictionary containing local variables.
|
||
|
|
|
||
|
|
attribs (list | None):
|
||
|
|
List of attribs for the given class. This is necessary when calling
|
||
|
|
from inside a ``field_transformer`` since *cls* is not an *attrs*
|
||
|
|
class yet.
|
||
|
|
|
||
|
|
include_extras (bool):
|
||
|
|
Resolve more accurately, if possible. Pass ``include_extras`` to
|
||
|
|
``typing.get_hints``, if supported by the typing module. On
|
||
|
|
supported Python versions (3.9+), this resolves the types more
|
||
|
|
accurately.
|
||
|
|
|
||
|
|
Raises:
|
||
|
|
TypeError: If *cls* is not a class.
|
||
|
|
|
||
|
|
attrs.exceptions.NotAnAttrsClassError:
|
||
|
|
If *cls* is not an *attrs* class and you didn't pass any attribs.
|
||
|
|
|
||
|
|
NameError: If types cannot be resolved because of missing variables.
|
||
|
|
|
||
|
|
Returns:
|
||
|
|
*cls* so you can use this function also as a class decorator. Please
|
||
|
|
note that you have to apply it **after** `attrs.define`. That means the
|
||
|
|
decorator has to come in the line **before** `attrs.define`.
|
||
|
|
|
||
|
|
.. versionadded:: 20.1.0
|
||
|
|
.. versionadded:: 21.1.0 *attribs*
|
||
|
|
.. versionadded:: 23.1.0 *include_extras*
|
||
|
|
"""
|
||
|
|
# Since calling get_type_hints is expensive we cache whether we've
|
||
|
|
# done it already.
|
||
|
|
if getattr(cls, "__attrs_types_resolved__", None) != cls:
|
||
|
|
import typing
|
||
|
|
|
||
|
|
kwargs = {"globalns": globalns, "localns": localns}
|
||
|
|
|
||
|
|
if PY_3_9_PLUS:
|
||
|
|
kwargs["include_extras"] = include_extras
|
||
|
|
|
||
|
|
hints = typing.get_type_hints(cls, **kwargs)
|
||
|
|
for field in fields(cls) if attribs is None else attribs:
|
||
|
|
if field.name in hints:
|
||
|
|
# Since fields have been frozen we must work around it.
|
||
|
|
_OBJ_SETATTR(field, "type", hints[field.name])
|
||
|
|
# We store the class we resolved so that subclasses know they haven't
|
||
|
|
# been resolved.
|
||
|
|
cls.__attrs_types_resolved__ = cls
|
||
|
|
|
||
|
|
# Return the class so you can use it as a decorator too.
|
||
|
|
return cls
|