390 lines
13 KiB
Python
390 lines
13 KiB
Python
from __future__ import absolute_import, division, print_function
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import copy
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from ._compat import iteritems
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from ._make import NOTHING, _obj_setattr, 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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:param inst: Instance of an ``attrs``-decorated class.
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:param bool recurse: Recurse into classes that are also
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``attrs``-decorated.
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:param callable filter: A callable whose return code determines whether an
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attribute or element is included (``True``) or dropped (``False``). Is
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called with the `attr.Attribute` as the first argument and the
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value as the second argument.
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:param callable dict_factory: A callable to produce dictionaries from. For
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example, to produce ordered dictionaries instead of normal Python
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dictionaries, pass in ``collections.OrderedDict``.
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:param bool retain_collection_types: Do not convert to ``list`` when
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encountering an attribute whose type is ``tuple`` or ``set``. Only
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meaningful if ``recurse`` is ``True``.
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:param Optional[callable] value_serializer: A hook that is called for every
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attribute or dict key/value. It receives the current instance, field
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and value and must return the (updated) value. The hook is run *after*
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the optional *filter* has been applied.
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:rtype: return type of *dict_factory*
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:raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
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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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"""
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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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True,
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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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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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rv[a.name] = cf(
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[
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_asdict_anything(
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i,
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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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for i in v
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]
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)
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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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filter,
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df,
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retain_collection_types,
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value_serializer,
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),
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_asdict_anything(
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vv,
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filter,
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df,
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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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for kk, vv in iteritems(v)
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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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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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True,
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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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elif isinstance(val, (tuple, list, set, frozenset)):
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cf = val.__class__ if retain_collection_types is True else 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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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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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, filter, df, retain_collection_types, value_serializer
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),
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_asdict_anything(
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vv, filter, df, retain_collection_types, value_serializer
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),
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)
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for kk, vv in iteritems(val)
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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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:param inst: Instance of an ``attrs``-decorated class.
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:param bool recurse: Recurse into classes that are also
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``attrs``-decorated.
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:param callable filter: A callable whose return code determines whether an
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attribute or element is included (``True``) or dropped (``False``). Is
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called with the `attr.Attribute` as the first argument and the
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value as the second argument.
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:param callable tuple_factory: A callable to produce tuples from. For
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example, to produce lists instead of tuples.
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:param bool retain_collection_types: Do not convert to ``list``
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or ``dict`` when encountering an attribute which type is
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``tuple``, ``dict`` or ``set``. Only meaningful if ``recurse`` is
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``True``.
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:rtype: return type of *tuple_factory*
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:raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
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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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rv.append(
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cf(
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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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for j in v
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]
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)
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)
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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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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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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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for kk, vv in iteritems(v)
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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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:param type cls: Class to introspect.
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:raise TypeError: If *cls* is not a class.
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:rtype: bool
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"""
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return getattr(cls, "__attrs_attrs__", None) is not None
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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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:param inst: Instance of a class with ``attrs`` attributes.
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:param changes: Keyword changes in the new copy.
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:return: A copy of inst with *changes* incorporated.
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:raise attr.exceptions.AttrsAttributeNotFoundError: If *attr_name* couldn't
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be found on *cls*.
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:raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
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class.
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.. deprecated:: 17.1.0
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Use `evolve` instead.
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"""
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import warnings
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warnings.warn(
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"assoc is deprecated and will be removed after 2018/01.",
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DeprecationWarning,
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stacklevel=2,
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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 iteritems(changes):
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a = getattr(attrs, k, NOTHING)
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if a is NOTHING:
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raise AttrsAttributeNotFoundError(
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"{k} is not an attrs attribute on {cl}.".format(
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k=k, cl=new.__class__
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)
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)
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_obj_setattr(new, k, v)
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return new
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def evolve(inst, **changes):
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"""
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Create a new instance, based on *inst* with *changes* applied.
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:param inst: Instance of a class with ``attrs`` attributes.
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:param changes: Keyword changes in the new copy.
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:return: A copy of inst with *changes* incorporated.
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:raise TypeError: If *attr_name* couldn't be found in the class
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``__init__``.
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:raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
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class.
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.. versionadded:: 17.1.0
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"""
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cls = inst.__class__
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attrs = fields(cls)
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for a in attrs:
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if not a.init:
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continue
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attr_name = a.name # To deal with private attributes.
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init_name = attr_name if attr_name[0] != "_" else attr_name[1:]
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if init_name not in changes:
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changes[init_name] = getattr(inst, attr_name)
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return cls(**changes)
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def resolve_types(cls, globalns=None, localns=None):
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"""
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Resolve any strings and forward annotations in type annotations.
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This is only required if you need concrete types in `Attribute`'s *type*
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field. In other words, you don't need to resolve your types if you only
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use them for static type checking.
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With no arguments, names will be looked up in the module in which the class
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was created. If this is not what you want, e.g. if the name only exists
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inside a method, you may pass *globalns* or *localns* to specify other
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dictionaries in which to look up these names. See the docs of
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`typing.get_type_hints` for more details.
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:param type cls: Class to resolve.
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:param Optional[dict] globalns: Dictionary containing global variables.
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:param Optional[dict] localns: Dictionary containing local variables.
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:raise TypeError: If *cls* is not a class.
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:raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
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class.
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:raise NameError: If types cannot be resolved because of missing variables.
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:returns: *cls* so you can use this function also as a class decorator.
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Please note that you have to apply it **after** `attr.s`. That means
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the decorator has to come in the line **before** `attr.s`.
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.. versionadded:: 20.1.0
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"""
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try:
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# Since calling get_type_hints is expensive we cache whether we've
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# done it already.
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cls.__attrs_types_resolved__
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except AttributeError:
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import typing
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hints = typing.get_type_hints(cls, globalns=globalns, localns=localns)
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for field in fields(cls):
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if field.name in hints:
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# Since fields have been frozen we must work around it.
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_obj_setattr(field, "type", hints[field.name])
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cls.__attrs_types_resolved__ = True
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# Return the class so you can use it as a decorator too.
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return cls
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