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Diffstat (limited to 'third_party/python/attrs/attr/_make.py')
| -rw-r--r-- | third_party/python/attrs/attr/_make.py | 2987 |
1 files changed, 2987 insertions, 0 deletions
diff --git a/third_party/python/attrs/attr/_make.py b/third_party/python/attrs/attr/_make.py new file mode 100644 index 0000000000..d72f738eec --- /dev/null +++ b/third_party/python/attrs/attr/_make.py @@ -0,0 +1,2987 @@ +# SPDX-License-Identifier: MIT + +import copy +import enum +import linecache +import sys +import types +import typing + +from operator import itemgetter + +# We need to import _compat itself in addition to the _compat members to avoid +# having the thread-local in the globals here. +from . import _compat, _config, setters +from ._compat import ( + PY310, + _AnnotationExtractor, + get_generic_base, + set_closure_cell, +) +from .exceptions import ( + DefaultAlreadySetError, + FrozenInstanceError, + NotAnAttrsClassError, + UnannotatedAttributeError, +) + + +# This is used at least twice, so cache it here. +_obj_setattr = object.__setattr__ +_init_converter_pat = "__attr_converter_%s" +_init_factory_pat = "__attr_factory_%s" +_classvar_prefixes = ( + "typing.ClassVar", + "t.ClassVar", + "ClassVar", + "typing_extensions.ClassVar", +) +# we don't use a double-underscore prefix because that triggers +# name mangling when trying to create a slot for the field +# (when slots=True) +_hash_cache_field = "_attrs_cached_hash" + +_empty_metadata_singleton = types.MappingProxyType({}) + +# Unique object for unequivocal getattr() defaults. +_sentinel = object() + +_ng_default_on_setattr = setters.pipe(setters.convert, setters.validate) + + +class _Nothing(enum.Enum): + """ + Sentinel to indicate the lack of a value when ``None`` is ambiguous. + + If extending attrs, you can use ``typing.Literal[NOTHING]`` to show + that a value may be ``NOTHING``. + + .. versionchanged:: 21.1.0 ``bool(NOTHING)`` is now False. + .. versionchanged:: 22.2.0 ``NOTHING`` is now an ``enum.Enum`` variant. + """ + + NOTHING = enum.auto() + + def __repr__(self): + return "NOTHING" + + def __bool__(self): + return False + + +NOTHING = _Nothing.NOTHING +""" +Sentinel to indicate the lack of a value when ``None`` is ambiguous. +""" + + +class _CacheHashWrapper(int): + """ + An integer subclass that pickles / copies as None + + This is used for non-slots classes with ``cache_hash=True``, to avoid + serializing a potentially (even likely) invalid hash value. Since ``None`` + is the default value for uncalculated hashes, whenever this is copied, + the copy's value for the hash should automatically reset. + + See GH #613 for more details. + """ + + def __reduce__(self, _none_constructor=type(None), _args=()): + return _none_constructor, _args + + +def attrib( + default=NOTHING, + validator=None, + repr=True, + cmp=None, + hash=None, + init=True, + metadata=None, + type=None, + converter=None, + factory=None, + kw_only=False, + eq=None, + order=None, + on_setattr=None, + alias=None, +): + """ + Create a new attribute on a class. + + .. warning:: + + Does *not* do anything unless the class is also decorated with + `attr.s` / `attrs.define` / et cetera! + + Please consider using `attrs.field` in new code (``attr.ib`` will *never* + go away, though). + + :param default: A value that is used if an *attrs*-generated ``__init__`` + is used and no value is passed while instantiating or the attribute is + excluded using ``init=False``. + + If the value is an instance of `attrs.Factory`, its callable will be + used to construct a new value (useful for mutable data types like lists + or dicts). + + If a default is not set (or set manually to `attrs.NOTHING`), a value + *must* be supplied when instantiating; otherwise a `TypeError` + will be raised. + + The default can also be set using decorator notation as shown below. + + :type default: Any value + + :param callable factory: Syntactic sugar for + ``default=attr.Factory(factory)``. + + :param validator: `callable` that is called by *attrs*-generated + ``__init__`` methods after the instance has been initialized. They + receive the initialized instance, the :func:`~attrs.Attribute`, and the + passed value. + + The return value is *not* inspected so the validator has to throw an + exception itself. + + If a `list` is passed, its items are treated as validators and must + all pass. + + Validators can be globally disabled and re-enabled using + `attrs.validators.get_disabled` / `attrs.validators.set_disabled`. + + The validator can also be set using decorator notation as shown below. + + :type validator: `callable` or a `list` of `callable`\\ s. + + :param repr: Include this attribute in the generated ``__repr__`` + method. If ``True``, include the attribute; if ``False``, omit it. By + default, the built-in ``repr()`` function is used. To override how the + attribute value is formatted, pass a ``callable`` that takes a single + value and returns a string. Note that the resulting string is used + as-is, i.e. it will be used directly *instead* of calling ``repr()`` + (the default). + :type repr: a `bool` or a `callable` to use a custom function. + + :param eq: If ``True`` (default), include this attribute in the + generated ``__eq__`` and ``__ne__`` methods that check two instances + for equality. To override how the attribute value is compared, + pass a ``callable`` that takes a single value and returns the value + to be compared. + :type eq: a `bool` or a `callable`. + + :param order: If ``True`` (default), include this attributes in the + generated ``__lt__``, ``__le__``, ``__gt__`` and ``__ge__`` methods. + To override how the attribute value is ordered, + pass a ``callable`` that takes a single value and returns the value + to be ordered. + :type order: a `bool` or a `callable`. + + :param cmp: Setting *cmp* is equivalent to setting *eq* and *order* to the + same value. Must not be mixed with *eq* or *order*. + :type cmp: a `bool` or a `callable`. + + :param Optional[bool] hash: Include this attribute in the generated + ``__hash__`` method. If ``None`` (default), mirror *eq*'s value. This + is the correct behavior according the Python spec. Setting this value + to anything else than ``None`` is *discouraged*. + :param bool init: Include this attribute in the generated ``__init__`` + method. It is possible to set this to ``False`` and set a default + value. In that case this attributed is unconditionally initialized + with the specified default value or factory. + :param callable converter: `callable` that is called by + *attrs*-generated ``__init__`` methods to convert attribute's value + to the desired format. It is given the passed-in value, and the + returned value will be used as the new value of the attribute. The + value is converted before being passed to the validator, if any. + :param metadata: An arbitrary mapping, to be used by third-party + components. See `extending-metadata`. + + :param type: The type of the attribute. Nowadays, the preferred method to + specify the type is using a variable annotation (see :pep:`526`). + This argument is provided for backward compatibility. + Regardless of the approach used, the type will be stored on + ``Attribute.type``. + + Please note that *attrs* doesn't do anything with this metadata by + itself. You can use it as part of your own code or for + `static type checking <types>`. + :param kw_only: Make this attribute keyword-only in the generated + ``__init__`` (if ``init`` is ``False``, this parameter is ignored). + :param on_setattr: Allows to overwrite the *on_setattr* setting from + `attr.s`. If left `None`, the *on_setattr* value from `attr.s` is used. + Set to `attrs.setters.NO_OP` to run **no** `setattr` hooks for this + attribute -- regardless of the setting in `attr.s`. + :type on_setattr: `callable`, or a list of callables, or `None`, or + `attrs.setters.NO_OP` + :param Optional[str] alias: Override this attribute's parameter name in the + generated ``__init__`` method. If left `None`, default to ``name`` + stripped of leading underscores. See `private-attributes`. + + .. versionadded:: 15.2.0 *convert* + .. versionadded:: 16.3.0 *metadata* + .. versionchanged:: 17.1.0 *validator* can be a ``list`` now. + .. versionchanged:: 17.1.0 + *hash* is ``None`` and therefore mirrors *eq* by default. + .. versionadded:: 17.3.0 *type* + .. deprecated:: 17.4.0 *convert* + .. versionadded:: 17.4.0 *converter* as a replacement for the deprecated + *convert* to achieve consistency with other noun-based arguments. + .. versionadded:: 18.1.0 + ``factory=f`` is syntactic sugar for ``default=attr.Factory(f)``. + .. versionadded:: 18.2.0 *kw_only* + .. versionchanged:: 19.2.0 *convert* keyword argument removed. + .. versionchanged:: 19.2.0 *repr* also accepts a custom callable. + .. deprecated:: 19.2.0 *cmp* Removal on or after 2021-06-01. + .. versionadded:: 19.2.0 *eq* and *order* + .. versionadded:: 20.1.0 *on_setattr* + .. versionchanged:: 20.3.0 *kw_only* backported to Python 2 + .. versionchanged:: 21.1.0 + *eq*, *order*, and *cmp* also accept a custom callable + .. versionchanged:: 21.1.0 *cmp* undeprecated + .. versionadded:: 22.2.0 *alias* + """ + eq, eq_key, order, order_key = _determine_attrib_eq_order( + cmp, eq, order, True + ) + + if hash is not None and hash is not True and hash is not False: + raise TypeError( + "Invalid value for hash. Must be True, False, or None." + ) + + if factory is not None: + if default is not NOTHING: + raise ValueError( + "The `default` and `factory` arguments are mutually " + "exclusive." + ) + if not callable(factory): + raise ValueError("The `factory` argument must be a callable.") + default = Factory(factory) + + if metadata is None: + metadata = {} + + # Apply syntactic sugar by auto-wrapping. + if isinstance(on_setattr, (list, tuple)): + on_setattr = setters.pipe(*on_setattr) + + if validator and isinstance(validator, (list, tuple)): + validator = and_(*validator) + + if converter and isinstance(converter, (list, tuple)): + converter = pipe(*converter) + + return _CountingAttr( + default=default, + validator=validator, + repr=repr, + cmp=None, + hash=hash, + init=init, + converter=converter, + metadata=metadata, + type=type, + kw_only=kw_only, + eq=eq, + eq_key=eq_key, + order=order, + order_key=order_key, + on_setattr=on_setattr, + alias=alias, + ) + + +def _compile_and_eval(script, globs, locs=None, filename=""): + """ + "Exec" the script with the given global (globs) and local (locs) variables. + """ + bytecode = compile(script, filename, "exec") + eval(bytecode, globs, locs) + + +def _make_method(name, script, filename, globs): + """ + Create the method with the script given and return the method object. + """ + locs = {} + + # In order of debuggers like PDB being able to step through the code, + # we add a fake linecache entry. + count = 1 + base_filename = filename + while True: + linecache_tuple = ( + len(script), + None, + script.splitlines(True), + filename, + ) + old_val = linecache.cache.setdefault(filename, linecache_tuple) + if old_val == linecache_tuple: + break + else: + filename = f"{base_filename[:-1]}-{count}>" + count += 1 + + _compile_and_eval(script, globs, locs, filename) + + return locs[name] + + +def _make_attr_tuple_class(cls_name, attr_names): + """ + Create a tuple subclass to hold `Attribute`s for an `attrs` class. + + The subclass is a bare tuple with properties for names. + + class MyClassAttributes(tuple): + __slots__ = () + x = property(itemgetter(0)) + """ + attr_class_name = f"{cls_name}Attributes" + attr_class_template = [ + f"class {attr_class_name}(tuple):", + " __slots__ = ()", + ] + if attr_names: + for i, attr_name in enumerate(attr_names): + attr_class_template.append( + f" {attr_name} = _attrs_property(_attrs_itemgetter({i}))" + ) + else: + attr_class_template.append(" pass") + globs = {"_attrs_itemgetter": itemgetter, "_attrs_property": property} + _compile_and_eval("\n".join(attr_class_template), globs) + return globs[attr_class_name] + + +# Tuple class for extracted attributes from a class definition. +# `base_attrs` is a subset of `attrs`. +_Attributes = _make_attr_tuple_class( + "_Attributes", + [ + # all attributes to build dunder methods for + "attrs", + # attributes that have been inherited + "base_attrs", + # map inherited attributes to their originating classes + "base_attrs_map", + ], +) + + +def _is_class_var(annot): + """ + Check whether *annot* is a typing.ClassVar. + + The string comparison hack is used to avoid evaluating all string + annotations which would put attrs-based classes at a performance + disadvantage compared to plain old classes. + """ + annot = str(annot) + + # Annotation can be quoted. + if annot.startswith(("'", '"')) and annot.endswith(("'", '"')): + annot = annot[1:-1] + + return annot.startswith(_classvar_prefixes) + + +def _has_own_attribute(cls, attrib_name): + """ + Check whether *cls* defines *attrib_name* (and doesn't just inherit it). + """ + attr = getattr(cls, attrib_name, _sentinel) + if attr is _sentinel: + return False + + for base_cls in cls.__mro__[1:]: + a = getattr(base_cls, attrib_name, None) + if attr is a: + return False + + return True + + +def _get_annotations(cls): + """ + Get annotations for *cls*. + """ + if _has_own_attribute(cls, "__annotations__"): + return cls.__annotations__ + + return {} + + +def _collect_base_attrs(cls, taken_attr_names): + """ + Collect attr.ibs from base classes of *cls*, except *taken_attr_names*. + """ + base_attrs = [] + base_attr_map = {} # A dictionary of base attrs to their classes. + + # Traverse the MRO and collect attributes. + for base_cls in reversed(cls.__mro__[1:-1]): + for a in getattr(base_cls, "__attrs_attrs__", []): + if a.inherited or a.name in taken_attr_names: + continue + + a = a.evolve(inherited=True) + base_attrs.append(a) + base_attr_map[a.name] = base_cls + + # For each name, only keep the freshest definition i.e. the furthest at the + # back. base_attr_map is fine because it gets overwritten with every new + # instance. + filtered = [] + seen = set() + for a in reversed(base_attrs): + if a.name in seen: + continue + filtered.insert(0, a) + seen.add(a.name) + + return filtered, base_attr_map + + +def _collect_base_attrs_broken(cls, taken_attr_names): + """ + Collect attr.ibs from base classes of *cls*, except *taken_attr_names*. + + N.B. *taken_attr_names* will be mutated. + + Adhere to the old incorrect behavior. + + Notably it collects from the front and considers inherited attributes which + leads to the buggy behavior reported in #428. + """ + base_attrs = [] + base_attr_map = {} # A dictionary of base attrs to their classes. + + # Traverse the MRO and collect attributes. + for base_cls in cls.__mro__[1:-1]: + for a in getattr(base_cls, "__attrs_attrs__", []): + if a.name in taken_attr_names: + continue + + a = a.evolve(inherited=True) + taken_attr_names.add(a.name) + base_attrs.append(a) + base_attr_map[a.name] = base_cls + + return base_attrs, base_attr_map + + +def _transform_attrs( + cls, these, auto_attribs, kw_only, collect_by_mro, field_transformer +): + """ + Transform all `_CountingAttr`s on a class into `Attribute`s. + + If *these* is passed, use that and don't look for them on the class. + + *collect_by_mro* is True, collect them in the correct MRO order, otherwise + use the old -- incorrect -- order. See #428. + + Return an `_Attributes`. + """ + cd = cls.__dict__ + anns = _get_annotations(cls) + + if these is not None: + ca_list = [(name, ca) for name, ca in these.items()] + elif auto_attribs is True: + ca_names = { + name + for name, attr in cd.items() + if isinstance(attr, _CountingAttr) + } + ca_list = [] + annot_names = set() + for attr_name, type in anns.items(): + if _is_class_var(type): + continue + annot_names.add(attr_name) + a = cd.get(attr_name, NOTHING) + + if not isinstance(a, _CountingAttr): + if a is NOTHING: + a = attrib() + else: + a = attrib(default=a) + ca_list.append((attr_name, a)) + + unannotated = ca_names - annot_names + if len(unannotated) > 0: + raise UnannotatedAttributeError( + "The following `attr.ib`s lack a type annotation: " + + ", ".join( + sorted(unannotated, key=lambda n: cd.get(n).counter) + ) + + "." + ) + else: + ca_list = sorted( + ( + (name, attr) + for name, attr in cd.items() + if isinstance(attr, _CountingAttr) + ), + key=lambda e: e[1].counter, + ) + + own_attrs = [ + Attribute.from_counting_attr( + name=attr_name, ca=ca, type=anns.get(attr_name) + ) + for attr_name, ca in ca_list + ] + + if collect_by_mro: + base_attrs, base_attr_map = _collect_base_attrs( + cls, {a.name for a in own_attrs} + ) + else: + base_attrs, base_attr_map = _collect_base_attrs_broken( + cls, {a.name for a in own_attrs} + ) + + if kw_only: + own_attrs = [a.evolve(kw_only=True) for a in own_attrs] + base_attrs = [a.evolve(kw_only=True) for a in base_attrs] + + attrs = base_attrs + own_attrs + + # Mandatory vs non-mandatory attr order only matters when they are part of + # the __init__ signature and when they aren't kw_only (which are moved to + # the end and can be mandatory or non-mandatory in any order, as they will + # be specified as keyword args anyway). Check the order of those attrs: + had_default = False + for a in (a for a in attrs if a.init is not False and a.kw_only is False): + if had_default is True and a.default is NOTHING: + raise ValueError( + "No mandatory attributes allowed after an attribute with a " + f"default value or factory. Attribute in question: {a!r}" + ) + + if had_default is False and a.default is not NOTHING: + had_default = True + + if field_transformer is not None: + attrs = field_transformer(cls, attrs) + + # Resolve default field alias after executing field_transformer. + # This allows field_transformer to differentiate between explicit vs + # default aliases and supply their own defaults. + attrs = [ + a.evolve(alias=_default_init_alias_for(a.name)) if not a.alias else a + for a in attrs + ] + + # Create AttrsClass *after* applying the field_transformer since it may + # add or remove attributes! + attr_names = [a.name for a in attrs] + AttrsClass = _make_attr_tuple_class(cls.__name__, attr_names) + + return _Attributes((AttrsClass(attrs), base_attrs, base_attr_map)) + + +def _frozen_setattrs(self, name, value): + """ + Attached to frozen classes as __setattr__. + """ + if isinstance(self, BaseException) and name in ( + "__cause__", + "__context__", + "__traceback__", + ): + BaseException.__setattr__(self, name, value) + return + + raise FrozenInstanceError() + + +def _frozen_delattrs(self, name): + """ + Attached to frozen classes as __delattr__. + """ + raise FrozenInstanceError() + + +class _ClassBuilder: + """ + Iteratively build *one* class. + """ + + __slots__ = ( + "_attr_names", + "_attrs", + "_base_attr_map", + "_base_names", + "_cache_hash", + "_cls", + "_cls_dict", + "_delete_attribs", + "_frozen", + "_has_pre_init", + "_has_post_init", + "_is_exc", + "_on_setattr", + "_slots", + "_weakref_slot", + "_wrote_own_setattr", + "_has_custom_setattr", + ) + + def __init__( + self, + cls, + these, + slots, + frozen, + weakref_slot, + getstate_setstate, + auto_attribs, + kw_only, + cache_hash, + is_exc, + collect_by_mro, + on_setattr, + has_custom_setattr, + field_transformer, + ): + attrs, base_attrs, base_map = _transform_attrs( + cls, + these, + auto_attribs, + kw_only, + collect_by_mro, + field_transformer, + ) + + self._cls = cls + self._cls_dict = dict(cls.__dict__) if slots else {} + self._attrs = attrs + self._base_names = {a.name for a in base_attrs} + self._base_attr_map = base_map + self._attr_names = tuple(a.name for a in attrs) + self._slots = slots + self._frozen = frozen + self._weakref_slot = weakref_slot + self._cache_hash = cache_hash + self._has_pre_init = bool(getattr(cls, "__attrs_pre_init__", False)) + self._has_post_init = bool(getattr(cls, "__attrs_post_init__", False)) + self._delete_attribs = not bool(these) + self._is_exc = is_exc + self._on_setattr = on_setattr + + self._has_custom_setattr = has_custom_setattr + self._wrote_own_setattr = False + + self._cls_dict["__attrs_attrs__"] = self._attrs + + if frozen: + self._cls_dict["__setattr__"] = _frozen_setattrs + self._cls_dict["__delattr__"] = _frozen_delattrs + + self._wrote_own_setattr = True + elif on_setattr in ( + _ng_default_on_setattr, + setters.validate, + setters.convert, + ): + has_validator = has_converter = False + for a in attrs: + if a.validator is not None: + has_validator = True + if a.converter is not None: + has_converter = True + + if has_validator and has_converter: + break + if ( + ( + on_setattr == _ng_default_on_setattr + and not (has_validator or has_converter) + ) + or (on_setattr == setters.validate and not has_validator) + or (on_setattr == setters.convert and not has_converter) + ): + # If class-level on_setattr is set to convert + validate, but + # there's no field to convert or validate, pretend like there's + # no on_setattr. + self._on_setattr = None + + if getstate_setstate: + ( + self._cls_dict["__getstate__"], + self._cls_dict["__setstate__"], + ) = self._make_getstate_setstate() + + def __repr__(self): + return f"<_ClassBuilder(cls={self._cls.__name__})>" + + if PY310: + import abc + + def build_class(self): + """ + Finalize class based on the accumulated configuration. + + Builder cannot be used after calling this method. + """ + if self._slots is True: + return self._create_slots_class() + + return self.abc.update_abstractmethods( + self._patch_original_class() + ) + + else: + + def build_class(self): + """ + Finalize class based on the accumulated configuration. + + Builder cannot be used after calling this method. + """ + if self._slots is True: + return self._create_slots_class() + + return self._patch_original_class() + + def _patch_original_class(self): + """ + Apply accumulated methods and return the class. + """ + cls = self._cls + base_names = self._base_names + + # Clean class of attribute definitions (`attr.ib()`s). + if self._delete_attribs: + for name in self._attr_names: + if ( + name not in base_names + and getattr(cls, name, _sentinel) is not _sentinel + ): + try: + delattr(cls, name) + except AttributeError: + # This can happen if a base class defines a class + # variable and we want to set an attribute with the + # same name by using only a type annotation. + pass + + # Attach our dunder methods. + for name, value in self._cls_dict.items(): + setattr(cls, name, value) + + # If we've inherited an attrs __setattr__ and don't write our own, + # reset it to object's. + if not self._wrote_own_setattr and getattr( + cls, "__attrs_own_setattr__", False + ): + cls.__attrs_own_setattr__ = False + + if not self._has_custom_setattr: + cls.__setattr__ = _obj_setattr + + return cls + + def _create_slots_class(self): + """ + Build and return a new class with a `__slots__` attribute. + """ + cd = { + k: v + for k, v in self._cls_dict.items() + if k not in tuple(self._attr_names) + ("__dict__", "__weakref__") + } + + # If our class doesn't have its own implementation of __setattr__ + # (either from the user or by us), check the bases, if one of them has + # an attrs-made __setattr__, that needs to be reset. We don't walk the + # MRO because we only care about our immediate base classes. + # XXX: This can be confused by subclassing a slotted attrs class with + # XXX: a non-attrs class and subclass the resulting class with an attrs + # XXX: class. See `test_slotted_confused` for details. For now that's + # XXX: OK with us. + if not self._wrote_own_setattr: + cd["__attrs_own_setattr__"] = False + + if not self._has_custom_setattr: + for base_cls in self._cls.__bases__: + if base_cls.__dict__.get("__attrs_own_setattr__", False): + cd["__setattr__"] = _obj_setattr + break + + # Traverse the MRO to collect existing slots + # and check for an existing __weakref__. + existing_slots = dict() + weakref_inherited = False + for base_cls in self._cls.__mro__[1:-1]: + if base_cls.__dict__.get("__weakref__", None) is not None: + weakref_inherited = True + existing_slots.update( + { + name: getattr(base_cls, name) + for name in getattr(base_cls, "__slots__", []) + } + ) + + base_names = set(self._base_names) + + names = self._attr_names + if ( + self._weakref_slot + and "__weakref__" not in getattr(self._cls, "__slots__", ()) + and "__weakref__" not in names + and not weakref_inherited + ): + names += ("__weakref__",) + + # We only add the names of attributes that aren't inherited. + # Setting __slots__ to inherited attributes wastes memory. + slot_names = [name for name in names if name not in base_names] + # There are slots for attributes from current class + # that are defined in parent classes. + # As their descriptors may be overridden by a child class, + # we collect them here and update the class dict + reused_slots = { + slot: slot_descriptor + for slot, slot_descriptor in existing_slots.items() + if slot in slot_names + } + slot_names = [name for name in slot_names if name not in reused_slots] + cd.update(reused_slots) + if self._cache_hash: + slot_names.append(_hash_cache_field) + cd["__slots__"] = tuple(slot_names) + + cd["__qualname__"] = self._cls.__qualname__ + + # Create new class based on old class and our methods. + cls = type(self._cls)(self._cls.__name__, self._cls.__bases__, cd) + + # The following is a fix for + # <https://github.com/python-attrs/attrs/issues/102>. + # If a method mentions `__class__` or uses the no-arg super(), the + # compiler will bake a reference to the class in the method itself + # as `method.__closure__`. Since we replace the class with a + # clone, we rewrite these references so it keeps working. + for item in cls.__dict__.values(): + if isinstance(item, (classmethod, staticmethod)): + # Class- and staticmethods hide their functions inside. + # These might need to be rewritten as well. + closure_cells = getattr(item.__func__, "__closure__", None) + elif isinstance(item, property): + # Workaround for property `super()` shortcut (PY3-only). + # There is no universal way for other descriptors. + closure_cells = getattr(item.fget, "__closure__", None) + else: + closure_cells = getattr(item, "__closure__", None) + + if not closure_cells: # Catch None or the empty list. + continue + for cell in closure_cells: + try: + match = cell.cell_contents is self._cls + except ValueError: # ValueError: Cell is empty + pass + else: + if match: + set_closure_cell(cell, cls) + + return cls + + def add_repr(self, ns): + self._cls_dict["__repr__"] = self._add_method_dunders( + _make_repr(self._attrs, ns, self._cls) + ) + return self + + def add_str(self): + repr = self._cls_dict.get("__repr__") + if repr is None: + raise ValueError( + "__str__ can only be generated if a __repr__ exists." + ) + + def __str__(self): + return self.__repr__() + + self._cls_dict["__str__"] = self._add_method_dunders(__str__) + return self + + def _make_getstate_setstate(self): + """ + Create custom __setstate__ and __getstate__ methods. + """ + # __weakref__ is not writable. + state_attr_names = tuple( + an for an in self._attr_names if an != "__weakref__" + ) + + def slots_getstate(self): + """ + Automatically created by attrs. + """ + return {name: getattr(self, name) for name in state_attr_names} + + hash_caching_enabled = self._cache_hash + + def slots_setstate(self, state): + """ + Automatically created by attrs. + """ + __bound_setattr = _obj_setattr.__get__(self) + if isinstance(state, tuple): + # Backward compatibility with attrs instances pickled with + # attrs versions before v22.2.0 which stored tuples. + for name, value in zip(state_attr_names, state): + __bound_setattr(name, value) + else: + for name in state_attr_names: + if name in state: + __bound_setattr(name, state[name]) + + # The hash code cache is not included when the object is + # serialized, but it still needs to be initialized to None to + # indicate that the first call to __hash__ should be a cache + # miss. + if hash_caching_enabled: + __bound_setattr(_hash_cache_field, None) + + return slots_getstate, slots_setstate + + def make_unhashable(self): + self._cls_dict["__hash__"] = None + return self + + def add_hash(self): + self._cls_dict["__hash__"] = self._add_method_dunders( + _make_hash( + self._cls, + self._attrs, + frozen=self._frozen, + cache_hash=self._cache_hash, + ) + ) + + return self + + def add_init(self): + self._cls_dict["__init__"] = self._add_method_dunders( + _make_init( + self._cls, + self._attrs, + self._has_pre_init, + self._has_post_init, + self._frozen, + self._slots, + self._cache_hash, + self._base_attr_map, + self._is_exc, + self._on_setattr, + attrs_init=False, + ) + ) + + return self + + def add_match_args(self): + self._cls_dict["__match_args__"] = tuple( + field.name + for field in self._attrs + if field.init and not field.kw_only + ) + + def add_attrs_init(self): + self._cls_dict["__attrs_init__"] = self._add_method_dunders( + _make_init( + self._cls, + self._attrs, + self._has_pre_init, + self._has_post_init, + self._frozen, + self._slots, + self._cache_hash, + self._base_attr_map, + self._is_exc, + self._on_setattr, + attrs_init=True, + ) + ) + + return self + + def add_eq(self): + cd = self._cls_dict + + cd["__eq__"] = self._add_method_dunders( + _make_eq(self._cls, self._attrs) + ) + cd["__ne__"] = self._add_method_dunders(_make_ne()) + + return self + + def add_order(self): + cd = self._cls_dict + + cd["__lt__"], cd["__le__"], cd["__gt__"], cd["__ge__"] = ( + self._add_method_dunders(meth) + for meth in _make_order(self._cls, self._attrs) + ) + + return self + + def add_setattr(self): + if self._frozen: + return self + + sa_attrs = {} + for a in self._attrs: + on_setattr = a.on_setattr or self._on_setattr + if on_setattr and on_setattr is not setters.NO_OP: + sa_attrs[a.name] = a, on_setattr + + if not sa_attrs: + return self + + if self._has_custom_setattr: + # We need to write a __setattr__ but there already is one! + raise ValueError( + "Can't combine custom __setattr__ with on_setattr hooks." + ) + + # docstring comes from _add_method_dunders + def __setattr__(self, name, val): + try: + a, hook = sa_attrs[name] + except KeyError: + nval = val + else: + nval = hook(self, a, val) + + _obj_setattr(self, name, nval) + + self._cls_dict["__attrs_own_setattr__"] = True + self._cls_dict["__setattr__"] = self._add_method_dunders(__setattr__) + self._wrote_own_setattr = True + + return self + + def _add_method_dunders(self, method): + """ + Add __module__ and __qualname__ to a *method* if possible. + """ + try: + method.__module__ = self._cls.__module__ + except AttributeError: + pass + + try: + method.__qualname__ = ".".join( + (self._cls.__qualname__, method.__name__) + ) + except AttributeError: + pass + + try: + method.__doc__ = ( + "Method generated by attrs for class " + f"{self._cls.__qualname__}." + ) + except AttributeError: + pass + + return method + + +def _determine_attrs_eq_order(cmp, eq, order, default_eq): + """ + Validate the combination of *cmp*, *eq*, and *order*. Derive the effective + values of eq and order. If *eq* is None, set it to *default_eq*. + """ + if cmp is not None and any((eq is not None, order is not None)): + raise ValueError("Don't mix `cmp` with `eq' and `order`.") + + # cmp takes precedence due to bw-compatibility. + if cmp is not None: + return cmp, cmp + + # If left None, equality is set to the specified default and ordering + # mirrors equality. + if eq is None: + eq = default_eq + + if order is None: + order = eq + + if eq is False and order is True: + raise ValueError("`order` can only be True if `eq` is True too.") + + return eq, order + + +def _determine_attrib_eq_order(cmp, eq, order, default_eq): + """ + Validate the combination of *cmp*, *eq*, and *order*. Derive the effective + values of eq and order. If *eq* is None, set it to *default_eq*. + """ + if cmp is not None and any((eq is not None, order is not None)): + raise ValueError("Don't mix `cmp` with `eq' and `order`.") + + def decide_callable_or_boolean(value): + """ + Decide whether a key function is used. + """ + if callable(value): + value, key = True, value + else: + key = None + return value, key + + # cmp takes precedence due to bw-compatibility. + if cmp is not None: + cmp, cmp_key = decide_callable_or_boolean(cmp) + return cmp, cmp_key, cmp, cmp_key + + # If left None, equality is set to the specified default and ordering + # mirrors equality. + if eq is None: + eq, eq_key = default_eq, None + else: + eq, eq_key = decide_callable_or_boolean(eq) + + if order is None: + order, order_key = eq, eq_key + else: + order, order_key = decide_callable_or_boolean(order) + + if eq is False and order is True: + raise ValueError("`order` can only be True if `eq` is True too.") + + return eq, eq_key, order, order_key + + +def _determine_whether_to_implement( + cls, flag, auto_detect, dunders, default=True +): + """ + Check whether we should implement a set of methods for *cls*. + + *flag* is the argument passed into @attr.s like 'init', *auto_detect* the + same as passed into @attr.s and *dunders* is a tuple of attribute names + whose presence signal that the user has implemented it themselves. + + Return *default* if no reason for either for or against is found. + """ + if flag is True or flag is False: + return flag + + if flag is None and auto_detect is False: + return default + + # Logically, flag is None and auto_detect is True here. + for dunder in dunders: + if _has_own_attribute(cls, dunder): + return False + + return default + + +def attrs( + maybe_cls=None, + these=None, + repr_ns=None, + repr=None, + cmp=None, + hash=None, + init=None, + slots=False, + frozen=False, + weakref_slot=True, + str=False, + auto_attribs=False, + kw_only=False, + cache_hash=False, + auto_exc=False, + eq=None, + order=None, + auto_detect=False, + collect_by_mro=False, + getstate_setstate=None, + on_setattr=None, + field_transformer=None, + match_args=True, + unsafe_hash=None, +): + r""" + A class decorator that adds :term:`dunder methods` according to the + specified attributes using `attr.ib` or the *these* argument. + + Please consider using `attrs.define` / `attrs.frozen` in new code + (``attr.s`` will *never* go away, though). + + :param these: A dictionary of name to `attr.ib` mappings. This is + useful to avoid the definition of your attributes within the class body + because you can't (e.g. if you want to add ``__repr__`` methods to + Django models) or don't want to. + + If *these* is not ``None``, *attrs* will *not* search the class body + for attributes and will *not* remove any attributes from it. + + The order is deduced from the order of the attributes inside *these*. + + :type these: `dict` of `str` to `attr.ib` + + :param str repr_ns: When using nested classes, there's no way in Python 2 + to automatically detect that. Therefore it's possible to set the + namespace explicitly for a more meaningful ``repr`` output. + :param bool auto_detect: Instead of setting the *init*, *repr*, *eq*, + *order*, and *hash* arguments explicitly, assume they are set to + ``True`` **unless any** of the involved methods for one of the + arguments is implemented in the *current* class (i.e. it is *not* + inherited from some base class). + + So for example by implementing ``__eq__`` on a class yourself, + *attrs* will deduce ``eq=False`` and will create *neither* + ``__eq__`` *nor* ``__ne__`` (but Python classes come with a sensible + ``__ne__`` by default, so it *should* be enough to only implement + ``__eq__`` in most cases). + + .. warning:: + + If you prevent *attrs* from creating the ordering methods for you + (``order=False``, e.g. by implementing ``__le__``), it becomes + *your* responsibility to make sure its ordering is sound. The best + way is to use the `functools.total_ordering` decorator. + + + Passing ``True`` or ``False`` to *init*, *repr*, *eq*, *order*, + *cmp*, or *hash* overrides whatever *auto_detect* would determine. + + :param bool repr: Create a ``__repr__`` method with a human readable + representation of *attrs* attributes.. + :param bool str: Create a ``__str__`` method that is identical to + ``__repr__``. This is usually not necessary except for + `Exception`\ s. + :param Optional[bool] eq: If ``True`` or ``None`` (default), add ``__eq__`` + and ``__ne__`` methods that check two instances for equality. + + They compare the instances as if they were tuples of their *attrs* + attributes if and only if the types of both classes are *identical*! + :param Optional[bool] order: If ``True``, add ``__lt__``, ``__le__``, + ``__gt__``, and ``__ge__`` methods that behave like *eq* above and + allow instances to be ordered. If ``None`` (default) mirror value of + *eq*. + :param Optional[bool] cmp: Setting *cmp* is equivalent to setting *eq* + and *order* to the same value. Must not be mixed with *eq* or *order*. + :param Optional[bool] unsafe_hash: If ``None`` (default), the ``__hash__`` + method is generated according how *eq* and *frozen* are set. + + 1. If *both* are True, *attrs* will generate a ``__hash__`` for you. + 2. If *eq* is True and *frozen* is False, ``__hash__`` will be set to + None, marking it unhashable (which it is). + 3. If *eq* is False, ``__hash__`` will be left untouched meaning the + ``__hash__`` method of the base class will be used (if base class is + ``object``, this means it will fall back to id-based hashing.). + + Although not recommended, you can decide for yourself and force + *attrs* to create one (e.g. if the class is immutable even though you + didn't freeze it programmatically) by passing ``True`` or not. Both of + these cases are rather special and should be used carefully. + + See our documentation on `hashing`, Python's documentation on + `object.__hash__`, and the `GitHub issue that led to the default \ + behavior <https://github.com/python-attrs/attrs/issues/136>`_ for more + details. + :param Optional[bool] hash: Alias for *unsafe_hash*. *unsafe_hash* takes + precedence. + :param bool init: Create a ``__init__`` method that initializes the + *attrs* attributes. Leading underscores are stripped for the argument + name. If a ``__attrs_pre_init__`` method exists on the class, it will + be called before the class is initialized. If a ``__attrs_post_init__`` + method exists on the class, it will be called after the class is fully + initialized. + + If ``init`` is ``False``, an ``__attrs_init__`` method will be + injected instead. This allows you to define a custom ``__init__`` + method that can do pre-init work such as ``super().__init__()``, + and then call ``__attrs_init__()`` and ``__attrs_post_init__()``. + :param bool slots: Create a :term:`slotted class <slotted classes>` that's + more memory-efficient. Slotted classes are generally superior to the + default dict classes, but have some gotchas you should know about, so + we encourage you to read the :term:`glossary entry <slotted classes>`. + :param bool frozen: Make instances immutable after initialization. If + someone attempts to modify a frozen instance, + `attrs.exceptions.FrozenInstanceError` is raised. + + .. note:: + + 1. This is achieved by installing a custom ``__setattr__`` method + on your class, so you can't implement your own. + + 2. True immutability is impossible in Python. + + 3. This *does* have a minor a runtime performance `impact + <how-frozen>` when initializing new instances. In other words: + ``__init__`` is slightly slower with ``frozen=True``. + + 4. If a class is frozen, you cannot modify ``self`` in + ``__attrs_post_init__`` or a self-written ``__init__``. You can + circumvent that limitation by using + ``object.__setattr__(self, "attribute_name", value)``. + + 5. Subclasses of a frozen class are frozen too. + + :param bool weakref_slot: Make instances weak-referenceable. This has no + effect unless ``slots`` is also enabled. + :param bool auto_attribs: If ``True``, collect :pep:`526`-annotated + attributes from the class body. + + In this case, you **must** annotate every field. If *attrs* + encounters a field that is set to an `attr.ib` but lacks a type + annotation, an `attr.exceptions.UnannotatedAttributeError` is + raised. Use ``field_name: typing.Any = attr.ib(...)`` if you don't + want to set a type. + + If you assign a value to those attributes (e.g. ``x: int = 42``), that + value becomes the default value like if it were passed using + ``attr.ib(default=42)``. Passing an instance of `attrs.Factory` also + works as expected in most cases (see warning below). + + Attributes annotated as `typing.ClassVar`, and attributes that are + neither annotated nor set to an `attr.ib` are **ignored**. + + .. warning:: + For features that use the attribute name to create decorators (e.g. + :ref:`validators <validators>`), you still *must* assign `attr.ib` + to them. Otherwise Python will either not find the name or try to + use the default value to call e.g. ``validator`` on it. + + These errors can be quite confusing and probably the most common bug + report on our bug tracker. + + :param bool kw_only: Make all attributes keyword-only + in the generated ``__init__`` (if ``init`` is ``False``, this + parameter is ignored). + :param bool cache_hash: Ensure that the object's hash code is computed + only once and stored on the object. If this is set to ``True``, + hashing must be either explicitly or implicitly enabled for this + class. If the hash code is cached, avoid any reassignments of + fields involved in hash code computation or mutations of the objects + those fields point to after object creation. If such changes occur, + the behavior of the object's hash code is undefined. + :param bool auto_exc: If the class subclasses `BaseException` + (which implicitly includes any subclass of any exception), the + following happens to behave like a well-behaved Python exceptions + class: + + - the values for *eq*, *order*, and *hash* are ignored and the + instances compare and hash by the instance's ids (N.B. *attrs* will + *not* remove existing implementations of ``__hash__`` or the equality + methods. It just won't add own ones.), + - all attributes that are either passed into ``__init__`` or have a + default value are additionally available as a tuple in the ``args`` + attribute, + - the value of *str* is ignored leaving ``__str__`` to base classes. + :param bool collect_by_mro: Setting this to `True` fixes the way *attrs* + collects attributes from base classes. The default behavior is + incorrect in certain cases of multiple inheritance. It should be on by + default but is kept off for backward-compatibility. + + See issue `#428 <https://github.com/python-attrs/attrs/issues/428>`_ for + more details. + + :param Optional[bool] getstate_setstate: + .. note:: + This is usually only interesting for slotted classes and you should + probably just set *auto_detect* to `True`. + + If `True`, ``__getstate__`` and + ``__setstate__`` are generated and attached to the class. This is + necessary for slotted classes to be pickleable. If left `None`, it's + `True` by default for slotted classes and ``False`` for dict classes. + + If *auto_detect* is `True`, and *getstate_setstate* is left `None`, + and **either** ``__getstate__`` or ``__setstate__`` is detected directly + on the class (i.e. not inherited), it is set to `False` (this is usually + what you want). + + :param on_setattr: A callable that is run whenever the user attempts to set + an attribute (either by assignment like ``i.x = 42`` or by using + `setattr` like ``setattr(i, "x", 42)``). It receives the same arguments + as validators: the instance, the attribute that is being modified, and + the new value. + + If no exception is raised, the attribute is set to the return value of + the callable. + + If a list of callables is passed, they're automatically wrapped in an + `attrs.setters.pipe`. + :type on_setattr: `callable`, or a list of callables, or `None`, or + `attrs.setters.NO_OP` + + :param Optional[callable] field_transformer: + A function that is called with the original class object and all + fields right before *attrs* finalizes the class. You can use + this, e.g., to automatically add converters or validators to + fields based on their types. See `transform-fields` for more details. + + :param bool match_args: + If `True` (default), set ``__match_args__`` on the class to support + :pep:`634` (Structural Pattern Matching). It is a tuple of all + non-keyword-only ``__init__`` parameter names on Python 3.10 and later. + Ignored on older Python versions. + + .. versionadded:: 16.0.0 *slots* + .. versionadded:: 16.1.0 *frozen* + .. versionadded:: 16.3.0 *str* + .. versionadded:: 16.3.0 Support for ``__attrs_post_init__``. + .. versionchanged:: 17.1.0 + *hash* supports ``None`` as value which is also the default now. + .. versionadded:: 17.3.0 *auto_attribs* + .. versionchanged:: 18.1.0 + If *these* is passed, no attributes are deleted from the class body. + .. versionchanged:: 18.1.0 If *these* is ordered, the order is retained. + .. versionadded:: 18.2.0 *weakref_slot* + .. deprecated:: 18.2.0 + ``__lt__``, ``__le__``, ``__gt__``, and ``__ge__`` now raise a + `DeprecationWarning` if the classes compared are subclasses of + each other. ``__eq`` and ``__ne__`` never tried to compared subclasses + to each other. + .. versionchanged:: 19.2.0 + ``__lt__``, ``__le__``, ``__gt__``, and ``__ge__`` now do not consider + subclasses comparable anymore. + .. versionadded:: 18.2.0 *kw_only* + .. versionadded:: 18.2.0 *cache_hash* + .. versionadded:: 19.1.0 *auto_exc* + .. deprecated:: 19.2.0 *cmp* Removal on or after 2021-06-01. + .. versionadded:: 19.2.0 *eq* and *order* + .. versionadded:: 20.1.0 *auto_detect* + .. versionadded:: 20.1.0 *collect_by_mro* + .. versionadded:: 20.1.0 *getstate_setstate* + .. versionadded:: 20.1.0 *on_setattr* + .. versionadded:: 20.3.0 *field_transformer* + .. versionchanged:: 21.1.0 + ``init=False`` injects ``__attrs_init__`` + .. versionchanged:: 21.1.0 Support for ``__attrs_pre_init__`` + .. versionchanged:: 21.1.0 *cmp* undeprecated + .. versionadded:: 21.3.0 *match_args* + .. versionadded:: 22.2.0 + *unsafe_hash* as an alias for *hash* (for :pep:`681` compliance). + """ + eq_, order_ = _determine_attrs_eq_order(cmp, eq, order, None) + + # unsafe_hash takes precedence due to PEP 681. + if unsafe_hash is not None: + hash = unsafe_hash + + if isinstance(on_setattr, (list, tuple)): + on_setattr = setters.pipe(*on_setattr) + + def wrap(cls): + is_frozen = frozen or _has_frozen_base_class(cls) + is_exc = auto_exc is True and issubclass(cls, BaseException) + has_own_setattr = auto_detect and _has_own_attribute( + cls, "__setattr__" + ) + + if has_own_setattr and is_frozen: + raise ValueError("Can't freeze a class with a custom __setattr__.") + + builder = _ClassBuilder( + cls, + these, + slots, + is_frozen, + weakref_slot, + _determine_whether_to_implement( + cls, + getstate_setstate, + auto_detect, + ("__getstate__", "__setstate__"), + default=slots, + ), + auto_attribs, + kw_only, + cache_hash, + is_exc, + collect_by_mro, + on_setattr, + has_own_setattr, + field_transformer, + ) + if _determine_whether_to_implement( + cls, repr, auto_detect, ("__repr__",) + ): + builder.add_repr(repr_ns) + if str is True: + builder.add_str() + + eq = _determine_whether_to_implement( + cls, eq_, auto_detect, ("__eq__", "__ne__") + ) + if not is_exc and eq is True: + builder.add_eq() + if not is_exc and _determine_whether_to_implement( + cls, order_, auto_detect, ("__lt__", "__le__", "__gt__", "__ge__") + ): + builder.add_order() + + builder.add_setattr() + + nonlocal hash + if ( + hash is None + and auto_detect is True + and _has_own_attribute(cls, "__hash__") + ): + hash = False + + if hash is not True and hash is not False and hash is not None: + # Can't use `hash in` because 1 == True for example. + raise TypeError( + "Invalid value for hash. Must be True, False, or None." + ) + elif hash is False or (hash is None and eq is False) or is_exc: + # Don't do anything. Should fall back to __object__'s __hash__ + # which is by id. + if cache_hash: + raise TypeError( + "Invalid value for cache_hash. To use hash caching," + " hashing must be either explicitly or implicitly " + "enabled." + ) + elif hash is True or ( + hash is None and eq is True and is_frozen is True + ): + # Build a __hash__ if told so, or if it's safe. + builder.add_hash() + else: + # Raise TypeError on attempts to hash. + if cache_hash: + raise TypeError( + "Invalid value for cache_hash. To use hash caching," + " hashing must be either explicitly or implicitly " + "enabled." + ) + builder.make_unhashable() + + if _determine_whether_to_implement( + cls, init, auto_detect, ("__init__",) + ): + builder.add_init() + else: + builder.add_attrs_init() + if cache_hash: + raise TypeError( + "Invalid value for cache_hash. To use hash caching," + " init must be True." + ) + + if ( + PY310 + and match_args + and not _has_own_attribute(cls, "__match_args__") + ): + builder.add_match_args() + + return builder.build_class() + + # 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) + + +_attrs = attrs +""" +Internal alias so we can use it in functions that take an argument called +*attrs*. +""" + + +def _has_frozen_base_class(cls): + """ + Check whether *cls* has a frozen ancestor by looking at its + __setattr__. + """ + return cls.__setattr__ is _frozen_setattrs + + +def _generate_unique_filename(cls, func_name): + """ + Create a "filename" suitable for a function being generated. + """ + return ( + f"<attrs generated {func_name} {cls.__module__}." + f"{getattr(cls, '__qualname__', cls.__name__)}>" + ) + + +def _make_hash(cls, attrs, frozen, cache_hash): + attrs = tuple( + a for a in attrs if a.hash is True or (a.hash is None and a.eq is True) + ) + + tab = " " + + unique_filename = _generate_unique_filename(cls, "hash") + type_hash = hash(unique_filename) + # If eq is custom generated, we need to include the functions in globs + globs = {} + + hash_def = "def __hash__(self" + hash_func = "hash((" + closing_braces = "))" + if not cache_hash: + hash_def += "):" + else: + hash_def += ", *" + + hash_def += ( + ", _cache_wrapper=" + + "__import__('attr._make')._make._CacheHashWrapper):" + ) + hash_func = "_cache_wrapper(" + hash_func + closing_braces += ")" + + method_lines = [hash_def] + + def append_hash_computation_lines(prefix, indent): + """ + Generate the code for actually computing the hash code. + Below this will either be returned directly or used to compute + a value which is then cached, depending on the value of cache_hash + """ + + method_lines.extend( + [ + indent + prefix + hash_func, + indent + f" {type_hash},", + ] + ) + + for a in attrs: + if a.eq_key: + cmp_name = f"_{a.name}_key" + globs[cmp_name] = a.eq_key + method_lines.append( + indent + f" {cmp_name}(self.{a.name})," + ) + else: + method_lines.append(indent + f" self.{a.name},") + + method_lines.append(indent + " " + closing_braces) + + if cache_hash: + method_lines.append(tab + f"if self.{_hash_cache_field} is None:") + if frozen: + append_hash_computation_lines( + f"object.__setattr__(self, '{_hash_cache_field}', ", tab * 2 + ) + method_lines.append(tab * 2 + ")") # close __setattr__ + else: + append_hash_computation_lines( + f"self.{_hash_cache_field} = ", tab * 2 + ) + method_lines.append(tab + f"return self.{_hash_cache_field}") + else: + append_hash_computation_lines("return ", tab) + + script = "\n".join(method_lines) + return _make_method("__hash__", script, unique_filename, globs) + + +def _add_hash(cls, attrs): + """ + Add a hash method to *cls*. + """ + cls.__hash__ = _make_hash(cls, attrs, frozen=False, cache_hash=False) + return cls + + +def _make_ne(): + """ + Create __ne__ method. + """ + + def __ne__(self, other): + """ + Check equality and either forward a NotImplemented or + return the result negated. + """ + result = self.__eq__(other) + if result is NotImplemented: + return NotImplemented + + return not result + + return __ne__ + + +def _make_eq(cls, attrs): + """ + Create __eq__ method for *cls* with *attrs*. + """ + attrs = [a for a in attrs if a.eq] + + unique_filename = _generate_unique_filename(cls, "eq") + lines = [ + "def __eq__(self, other):", + " if other.__class__ is not self.__class__:", + " return NotImplemented", + ] + + # We can't just do a big self.x = other.x and... clause due to + # irregularities like nan == nan is false but (nan,) == (nan,) is true. + globs = {} + if attrs: + lines.append(" return (") + others = [" ) == ("] + for a in attrs: + if a.eq_key: + cmp_name = f"_{a.name}_key" + # Add the key function to the global namespace + # of the evaluated function. + globs[cmp_name] = a.eq_key + lines.append(f" {cmp_name}(self.{a.name}),") + others.append(f" {cmp_name}(other.{a.name}),") + else: + lines.append(f" self.{a.name},") + others.append(f" other.{a.name},") + + lines += others + [" )"] + else: + lines.append(" return True") + + script = "\n".join(lines) + + return _make_method("__eq__", script, unique_filename, globs) + + +def _make_order(cls, attrs): + """ + Create ordering methods for *cls* with *attrs*. + """ + attrs = [a for a in attrs if a.order] + + def attrs_to_tuple(obj): + """ + Save us some typing. + """ + return tuple( + key(value) if key else value + for value, key in ( + (getattr(obj, a.name), a.order_key) for a in attrs + ) + ) + + def __lt__(self, other): + """ + Automatically created by attrs. + """ + if other.__class__ is self.__class__: + return attrs_to_tuple(self) < attrs_to_tuple(other) + + return NotImplemented + + def __le__(self, other): + """ + Automatically created by attrs. + """ + if other.__class__ is self.__class__: + return attrs_to_tuple(self) <= attrs_to_tuple(other) + + return NotImplemented + + def __gt__(self, other): + """ + Automatically created by attrs. + """ + if other.__class__ is self.__class__: + return attrs_to_tuple(self) > attrs_to_tuple(other) + + return NotImplemented + + def __ge__(self, other): + """ + Automatically created by attrs. + """ + if other.__class__ is self.__class__: + return attrs_to_tuple(self) >= attrs_to_tuple(other) + + return NotImplemented + + return __lt__, __le__, __gt__, __ge__ + + +def _add_eq(cls, attrs=None): + """ + Add equality methods to *cls* with *attrs*. + """ + if attrs is None: + attrs = cls.__attrs_attrs__ + + cls.__eq__ = _make_eq(cls, attrs) + cls.__ne__ = _make_ne() + + return cls + + +def _make_repr(attrs, ns, cls): + unique_filename = _generate_unique_filename(cls, "repr") + # Figure out which attributes to include, and which function to use to + # format them. The a.repr value can be either bool or a custom + # callable. + attr_names_with_reprs = tuple( + (a.name, (repr if a.repr is True else a.repr), a.init) + for a in attrs + if a.repr is not False + ) + globs = { + name + "_repr": r for name, r, _ in attr_names_with_reprs if r != repr + } + globs["_compat"] = _compat + globs["AttributeError"] = AttributeError + globs["NOTHING"] = NOTHING + attribute_fragments = [] + for name, r, i in attr_names_with_reprs: + accessor = ( + "self." + name if i else 'getattr(self, "' + name + '", NOTHING)' + ) + fragment = ( + "%s={%s!r}" % (name, accessor) + if r == repr + else "%s={%s_repr(%s)}" % (name, name, accessor) + ) + attribute_fragments.append(fragment) + repr_fragment = ", ".join(attribute_fragments) + + if ns is None: + cls_name_fragment = '{self.__class__.__qualname__.rsplit(">.", 1)[-1]}' + else: + cls_name_fragment = ns + ".{self.__class__.__name__}" + + lines = [ + "def __repr__(self):", + " try:", + " already_repring = _compat.repr_context.already_repring", + " except AttributeError:", + " already_repring = {id(self),}", + " _compat.repr_context.already_repring = already_repring", + " else:", + " if id(self) in already_repring:", + " return '...'", + " else:", + " already_repring.add(id(self))", + " try:", + f" return f'{cls_name_fragment}({repr_fragment})'", + " finally:", + " already_repring.remove(id(self))", + ] + + return _make_method( + "__repr__", "\n".join(lines), unique_filename, globs=globs + ) + + +def _add_repr(cls, ns=None, attrs=None): + """ + Add a repr method to *cls*. + """ + if attrs is None: + attrs = cls.__attrs_attrs__ + + cls.__repr__ = _make_repr(attrs, ns, cls) + return cls + + +def fields(cls): + """ + Return the tuple of *attrs* attributes for a class. + + The tuple also allows accessing the fields by their names (see below for + examples). + + :param type cls: Class to introspect. + + :raise TypeError: If *cls* is not a class. + :raise attrs.exceptions.NotAnAttrsClassError: If *cls* is not an *attrs* + class. + + :rtype: tuple (with name accessors) of `attrs.Attribute` + + .. versionchanged:: 16.2.0 Returned tuple allows accessing the fields + by name. + .. versionchanged:: 23.1.0 Add support for generic classes. + """ + generic_base = get_generic_base(cls) + + if generic_base is None and not isinstance(cls, type): + raise TypeError("Passed object must be a class.") + + attrs = getattr(cls, "__attrs_attrs__", None) + + if attrs is None: + if generic_base is not None: + attrs = getattr(generic_base, "__attrs_attrs__", None) + if attrs is not None: + # Even though this is global state, stick it on here to speed + # it up. We rely on `cls` being cached for this to be + # efficient. + cls.__attrs_attrs__ = attrs + return attrs + raise NotAnAttrsClassError(f"{cls!r} is not an attrs-decorated class.") + + return attrs + + +def fields_dict(cls): + """ + Return an ordered dictionary of *attrs* attributes for a class, whose + keys are the attribute names. + + :param type cls: Class to introspect. + + :raise TypeError: If *cls* is not a class. + :raise attrs.exceptions.NotAnAttrsClassError: If *cls* is not an *attrs* + class. + + :rtype: dict + + .. versionadded:: 18.1.0 + """ + if not isinstance(cls, type): + raise TypeError("Passed object must be a class.") + attrs = getattr(cls, "__attrs_attrs__", None) + if attrs is None: + raise NotAnAttrsClassError(f"{cls!r} is not an attrs-decorated class.") + return {a.name: a for a in attrs} + + +def validate(inst): + """ + Validate all attributes on *inst* that have a validator. + + Leaves all exceptions through. + + :param inst: Instance of a class with *attrs* attributes. + """ + if _config._run_validators is False: + return + + for a in fields(inst.__class__): + v = a.validator + if v is not None: + v(inst, a, getattr(inst, a.name)) + + +def _is_slot_cls(cls): + return "__slots__" in cls.__dict__ + + +def _is_slot_attr(a_name, base_attr_map): + """ + Check if the attribute name comes from a slot class. + """ + return a_name in base_attr_map and _is_slot_cls(base_attr_map[a_name]) + + +def _make_init( + cls, + attrs, + pre_init, + post_init, + frozen, + slots, + cache_hash, + base_attr_map, + is_exc, + cls_on_setattr, + attrs_init, +): + has_cls_on_setattr = ( + cls_on_setattr is not None and cls_on_setattr is not setters.NO_OP + ) + + if frozen and has_cls_on_setattr: + raise ValueError("Frozen classes can't use on_setattr.") + + needs_cached_setattr = cache_hash or frozen + filtered_attrs = [] + attr_dict = {} + for a in attrs: + if not a.init and a.default is NOTHING: + continue + + filtered_attrs.append(a) + attr_dict[a.name] = a + + if a.on_setattr is not None: + if frozen is True: + raise ValueError("Frozen classes can't use on_setattr.") + + needs_cached_setattr = True + elif has_cls_on_setattr and a.on_setattr is not setters.NO_OP: + needs_cached_setattr = True + + unique_filename = _generate_unique_filename(cls, "init") + + script, globs, annotations = _attrs_to_init_script( + filtered_attrs, + frozen, + slots, + pre_init, + post_init, + cache_hash, + base_attr_map, + is_exc, + needs_cached_setattr, + has_cls_on_setattr, + attrs_init, + ) + if cls.__module__ in sys.modules: + # This makes typing.get_type_hints(CLS.__init__) resolve string types. + globs.update(sys.modules[cls.__module__].__dict__) + + globs.update({"NOTHING": NOTHING, "attr_dict": attr_dict}) + + if needs_cached_setattr: + # Save the lookup overhead in __init__ if we need to circumvent + # setattr hooks. + globs["_cached_setattr_get"] = _obj_setattr.__get__ + + init = _make_method( + "__attrs_init__" if attrs_init else "__init__", + script, + unique_filename, + globs, + ) + init.__annotations__ = annotations + + return init + + +def _setattr(attr_name, value_var, has_on_setattr): + """ + Use the cached object.setattr to set *attr_name* to *value_var*. + """ + return f"_setattr('{attr_name}', {value_var})" + + +def _setattr_with_converter(attr_name, value_var, has_on_setattr): + """ + Use the cached object.setattr to set *attr_name* to *value_var*, but run + its converter first. + """ + return "_setattr('%s', %s(%s))" % ( + attr_name, + _init_converter_pat % (attr_name,), + value_var, + ) + + +def _assign(attr_name, value, has_on_setattr): + """ + Unless *attr_name* has an on_setattr hook, use normal assignment. Otherwise + relegate to _setattr. + """ + if has_on_setattr: + return _setattr(attr_name, value, True) + + return f"self.{attr_name} = {value}" + + +def _assign_with_converter(attr_name, value_var, has_on_setattr): + """ + Unless *attr_name* has an on_setattr hook, use normal assignment after + conversion. Otherwise relegate to _setattr_with_converter. + """ + if has_on_setattr: + return _setattr_with_converter(attr_name, value_var, True) + + return "self.%s = %s(%s)" % ( + attr_name, + _init_converter_pat % (attr_name,), + value_var, + ) + + +def _attrs_to_init_script( + attrs, + frozen, + slots, + pre_init, + post_init, + cache_hash, + base_attr_map, + is_exc, + needs_cached_setattr, + has_cls_on_setattr, + attrs_init, +): + """ + Return a script of an initializer for *attrs* and a dict of globals. + + The globals are expected by the generated script. + + If *frozen* is True, we cannot set the attributes directly so we use + a cached ``object.__setattr__``. + """ + lines = [] + if pre_init: + lines.append("self.__attrs_pre_init__()") + + if needs_cached_setattr: + lines.append( + # Circumvent the __setattr__ descriptor to save one lookup per + # assignment. + # Note _setattr will be used again below if cache_hash is True + "_setattr = _cached_setattr_get(self)" + ) + + if frozen is True: + if slots is True: + fmt_setter = _setattr + fmt_setter_with_converter = _setattr_with_converter + else: + # Dict frozen classes assign directly to __dict__. + # But only if the attribute doesn't come from an ancestor slot + # class. + # Note _inst_dict will be used again below if cache_hash is True + lines.append("_inst_dict = self.__dict__") + + def fmt_setter(attr_name, value_var, has_on_setattr): + if _is_slot_attr(attr_name, base_attr_map): + return _setattr(attr_name, value_var, has_on_setattr) + + return f"_inst_dict['{attr_name}'] = {value_var}" + + def fmt_setter_with_converter( + attr_name, value_var, has_on_setattr + ): + if has_on_setattr or _is_slot_attr(attr_name, base_attr_map): + return _setattr_with_converter( + attr_name, value_var, has_on_setattr + ) + + return "_inst_dict['%s'] = %s(%s)" % ( + attr_name, + _init_converter_pat % (attr_name,), + value_var, + ) + + else: + # Not frozen. + fmt_setter = _assign + fmt_setter_with_converter = _assign_with_converter + + args = [] + kw_only_args = [] + attrs_to_validate = [] + + # This is a dictionary of names to validator and converter callables. + # Injecting this into __init__ globals lets us avoid lookups. + names_for_globals = {} + annotations = {"return": None} + + for a in attrs: + if a.validator: + attrs_to_validate.append(a) + + attr_name = a.name + has_on_setattr = a.on_setattr is not None or ( + a.on_setattr is not setters.NO_OP and has_cls_on_setattr + ) + # a.alias is set to maybe-mangled attr_name in _ClassBuilder if not + # explicitly provided + arg_name = a.alias + + has_factory = isinstance(a.default, Factory) + if has_factory and a.default.takes_self: + maybe_self = "self" + else: + maybe_self = "" + + if a.init is False: + if has_factory: + init_factory_name = _init_factory_pat % (a.name,) + if a.converter is not None: + lines.append( + fmt_setter_with_converter( + attr_name, + init_factory_name + f"({maybe_self})", + has_on_setattr, + ) + ) + conv_name = _init_converter_pat % (a.name,) + names_for_globals[conv_name] = a.converter + else: + lines.append( + fmt_setter( + attr_name, + init_factory_name + f"({maybe_self})", + has_on_setattr, + ) + ) + names_for_globals[init_factory_name] = a.default.factory + else: + if a.converter is not None: + lines.append( + fmt_setter_with_converter( + attr_name, + f"attr_dict['{attr_name}'].default", + has_on_setattr, + ) + ) + conv_name = _init_converter_pat % (a.name,) + names_for_globals[conv_name] = a.converter + else: + lines.append( + fmt_setter( + attr_name, + f"attr_dict['{attr_name}'].default", + has_on_setattr, + ) + ) + elif a.default is not NOTHING and not has_factory: + arg = f"{arg_name}=attr_dict['{attr_name}'].default" + if a.kw_only: + kw_only_args.append(arg) + else: + args.append(arg) + + if a.converter is not None: + lines.append( + fmt_setter_with_converter( + attr_name, arg_name, has_on_setattr + ) + ) + names_for_globals[ + _init_converter_pat % (a.name,) + ] = a.converter + else: + lines.append(fmt_setter(attr_name, arg_name, has_on_setattr)) + + elif has_factory: + arg = f"{arg_name}=NOTHING" + if a.kw_only: + kw_only_args.append(arg) + else: + args.append(arg) + lines.append(f"if {arg_name} is not NOTHING:") + + init_factory_name = _init_factory_pat % (a.name,) + if a.converter is not None: + lines.append( + " " + + fmt_setter_with_converter( + attr_name, arg_name, has_on_setattr + ) + ) + lines.append("else:") + lines.append( + " " + + fmt_setter_with_converter( + attr_name, + init_factory_name + "(" + maybe_self + ")", + has_on_setattr, + ) + ) + names_for_globals[ + _init_converter_pat % (a.name,) + ] = a.converter + else: + lines.append( + " " + fmt_setter(attr_name, arg_name, has_on_setattr) + ) + lines.append("else:") + lines.append( + " " + + fmt_setter( + attr_name, + init_factory_name + "(" + maybe_self + ")", + has_on_setattr, + ) + ) + names_for_globals[init_factory_name] = a.default.factory + else: + if a.kw_only: + kw_only_args.append(arg_name) + else: + args.append(arg_name) + + if a.converter is not None: + lines.append( + fmt_setter_with_converter( + attr_name, arg_name, has_on_setattr + ) + ) + names_for_globals[ + _init_converter_pat % (a.name,) + ] = a.converter + else: + lines.append(fmt_setter(attr_name, arg_name, has_on_setattr)) + + if a.init is True: + if a.type is not None and a.converter is None: + annotations[arg_name] = a.type + elif a.converter is not None: + # Try to get the type from the converter. + t = _AnnotationExtractor(a.converter).get_first_param_type() + if t: + annotations[arg_name] = t + + if attrs_to_validate: # we can skip this if there are no validators. + names_for_globals["_config"] = _config + lines.append("if _config._run_validators is True:") + for a in attrs_to_validate: + val_name = "__attr_validator_" + a.name + attr_name = "__attr_" + a.name + lines.append(f" {val_name}(self, {attr_name}, self.{a.name})") + names_for_globals[val_name] = a.validator + names_for_globals[attr_name] = a + + if post_init: + lines.append("self.__attrs_post_init__()") + + # because this is set only after __attrs_post_init__ is called, a crash + # will result if post-init tries to access the hash code. This seemed + # preferable to setting this beforehand, in which case alteration to + # field values during post-init combined with post-init accessing the + # hash code would result in silent bugs. + if cache_hash: + if frozen: + if slots: + # if frozen and slots, then _setattr defined above + init_hash_cache = "_setattr('%s', %s)" + else: + # if frozen and not slots, then _inst_dict defined above + init_hash_cache = "_inst_dict['%s'] = %s" + else: + init_hash_cache = "self.%s = %s" + lines.append(init_hash_cache % (_hash_cache_field, "None")) + + # For exceptions we rely on BaseException.__init__ for proper + # initialization. + if is_exc: + vals = ",".join(f"self.{a.name}" for a in attrs if a.init) + + lines.append(f"BaseException.__init__(self, {vals})") + + args = ", ".join(args) + if kw_only_args: + args += "%s*, %s" % ( + ", " if args else "", # leading comma + ", ".join(kw_only_args), # kw_only args + ) + + return ( + "def %s(self, %s):\n %s\n" + % ( + ("__attrs_init__" if attrs_init else "__init__"), + args, + "\n ".join(lines) if lines else "pass", + ), + names_for_globals, + annotations, + ) + + +def _default_init_alias_for(name: str) -> str: + """ + The default __init__ parameter name for a field. + + This performs private-name adjustment via leading-unscore stripping, + and is the default value of Attribute.alias if not provided. + """ + + return name.lstrip("_") + + +class Attribute: + """ + *Read-only* representation of an attribute. + + .. warning:: + + You should never instantiate this class yourself. + + The class has *all* arguments of `attr.ib` (except for ``factory`` + which is only syntactic sugar for ``default=Factory(...)`` plus the + following: + + - ``name`` (`str`): The name of the attribute. + - ``alias`` (`str`): The __init__ parameter name of the attribute, after + any explicit overrides and default private-attribute-name handling. + - ``inherited`` (`bool`): Whether or not that attribute has been inherited + from a base class. + - ``eq_key`` and ``order_key`` (`typing.Callable` or `None`): The callables + that are used for comparing and ordering objects by this attribute, + respectively. These are set by passing a callable to `attr.ib`'s ``eq``, + ``order``, or ``cmp`` arguments. See also :ref:`comparison customization + <custom-comparison>`. + + Instances of this class are frequently used for introspection purposes + like: + + - `fields` returns a tuple of them. + - Validators get them passed as the first argument. + - The :ref:`field transformer <transform-fields>` hook receives a list of + them. + - The ``alias`` property exposes the __init__ parameter name of the field, + with any overrides and default private-attribute handling applied. + + + .. versionadded:: 20.1.0 *inherited* + .. versionadded:: 20.1.0 *on_setattr* + .. versionchanged:: 20.2.0 *inherited* is not taken into account for + equality checks and hashing anymore. + .. versionadded:: 21.1.0 *eq_key* and *order_key* + .. versionadded:: 22.2.0 *alias* + + For the full version history of the fields, see `attr.ib`. + """ + + __slots__ = ( + "name", + "default", + "validator", + "repr", + "eq", + "eq_key", + "order", + "order_key", + "hash", + "init", + "metadata", + "type", + "converter", + "kw_only", + "inherited", + "on_setattr", + "alias", + ) + + def __init__( + self, + name, + default, + validator, + repr, + cmp, # XXX: unused, remove along with other cmp code. + hash, + init, + inherited, + metadata=None, + type=None, + converter=None, + kw_only=False, + eq=None, + eq_key=None, + order=None, + order_key=None, + on_setattr=None, + alias=None, + ): + eq, eq_key, order, order_key = _determine_attrib_eq_order( + cmp, eq_key or eq, order_key or order, True + ) + + # Cache this descriptor here to speed things up later. + bound_setattr = _obj_setattr.__get__(self) + + # Despite the big red warning, people *do* instantiate `Attribute` + # themselves. + bound_setattr("name", name) + bound_setattr("default", default) + bound_setattr("validator", validator) + bound_setattr("repr", repr) + bound_setattr("eq", eq) + bound_setattr("eq_key", eq_key) + bound_setattr("order", order) + bound_setattr("order_key", order_key) + bound_setattr("hash", hash) + bound_setattr("init", init) + bound_setattr("converter", converter) + bound_setattr( + "metadata", + ( + types.MappingProxyType(dict(metadata)) # Shallow copy + if metadata + else _empty_metadata_singleton + ), + ) + bound_setattr("type", type) + bound_setattr("kw_only", kw_only) + bound_setattr("inherited", inherited) + bound_setattr("on_setattr", on_setattr) + bound_setattr("alias", alias) + + def __setattr__(self, name, value): + raise FrozenInstanceError() + + @classmethod + def from_counting_attr(cls, name, ca, type=None): + # type holds the annotated value. deal with conflicts: + if type is None: + type = ca.type + elif ca.type is not None: + raise ValueError( + "Type annotation and type argument cannot both be present" + ) + inst_dict = { + k: getattr(ca, k) + for k in Attribute.__slots__ + if k + not in ( + "name", + "validator", + "default", + "type", + "inherited", + ) # exclude methods and deprecated alias + } + return cls( + name=name, + validator=ca._validator, + default=ca._default, + type=type, + cmp=None, + inherited=False, + **inst_dict, + ) + + # Don't use attrs.evolve since fields(Attribute) doesn't work + def evolve(self, **changes): + """ + Copy *self* and apply *changes*. + + This works similarly to `attrs.evolve` but that function does not work + with `Attribute`. + + It is mainly meant to be used for `transform-fields`. + + .. versionadded:: 20.3.0 + """ + new = copy.copy(self) + + new._setattrs(changes.items()) + + return new + + # Don't use _add_pickle since fields(Attribute) doesn't work + def __getstate__(self): + """ + Play nice with pickle. + """ + return tuple( + getattr(self, name) if name != "metadata" else dict(self.metadata) + for name in self.__slots__ + ) + + def __setstate__(self, state): + """ + Play nice with pickle. + """ + self._setattrs(zip(self.__slots__, state)) + + def _setattrs(self, name_values_pairs): + bound_setattr = _obj_setattr.__get__(self) + for name, value in name_values_pairs: + if name != "metadata": + bound_setattr(name, value) + else: + bound_setattr( + name, + types.MappingProxyType(dict(value)) + if value + else _empty_metadata_singleton, + ) + + +_a = [ + Attribute( + name=name, + default=NOTHING, + validator=None, + repr=True, + cmp=None, + eq=True, + order=False, + hash=(name != "metadata"), + init=True, + inherited=False, + alias=_default_init_alias_for(name), + ) + for name in Attribute.__slots__ +] + +Attribute = _add_hash( + _add_eq( + _add_repr(Attribute, attrs=_a), + attrs=[a for a in _a if a.name != "inherited"], + ), + attrs=[a for a in _a if a.hash and a.name != "inherited"], +) + + +class _CountingAttr: + """ + Intermediate representation of attributes that uses a counter to preserve + the order in which the attributes have been defined. + + *Internal* data structure of the attrs library. Running into is most + likely the result of a bug like a forgotten `@attr.s` decorator. + """ + + __slots__ = ( + "counter", + "_default", + "repr", + "eq", + "eq_key", + "order", + "order_key", + "hash", + "init", + "metadata", + "_validator", + "converter", + "type", + "kw_only", + "on_setattr", + "alias", + ) + __attrs_attrs__ = tuple( + Attribute( + name=name, + alias=_default_init_alias_for(name), + default=NOTHING, + validator=None, + repr=True, + cmp=None, + hash=True, + init=True, + kw_only=False, + eq=True, + eq_key=None, + order=False, + order_key=None, + inherited=False, + on_setattr=None, + ) + for name in ( + "counter", + "_default", + "repr", + "eq", + "order", + "hash", + "init", + "on_setattr", + "alias", + ) + ) + ( + Attribute( + name="metadata", + alias="metadata", + default=None, + validator=None, + repr=True, + cmp=None, + hash=False, + init=True, + kw_only=False, + eq=True, + eq_key=None, + order=False, + order_key=None, + inherited=False, + on_setattr=None, + ), + ) + cls_counter = 0 + + def __init__( + self, + default, + validator, + repr, + cmp, + hash, + init, + converter, + metadata, + type, + kw_only, + eq, + eq_key, + order, + order_key, + on_setattr, + alias, + ): + _CountingAttr.cls_counter += 1 + self.counter = _CountingAttr.cls_counter + self._default = default + self._validator = validator + self.converter = converter + self.repr = repr + self.eq = eq + self.eq_key = eq_key + self.order = order + self.order_key = order_key + self.hash = hash + self.init = init + self.metadata = metadata + self.type = type + self.kw_only = kw_only + self.on_setattr = on_setattr + self.alias = alias + + def validator(self, meth): + """ + Decorator that adds *meth* to the list of validators. + + Returns *meth* unchanged. + + .. versionadded:: 17.1.0 + """ + if self._validator is None: + self._validator = meth + else: + self._validator = and_(self._validator, meth) + return meth + + def default(self, meth): + """ + Decorator that allows to set the default for an attribute. + + Returns *meth* unchanged. + + :raises DefaultAlreadySetError: If default has been set before. + + .. versionadded:: 17.1.0 + """ + if self._default is not NOTHING: + raise DefaultAlreadySetError() + + self._default = Factory(meth, takes_self=True) + + return meth + + +_CountingAttr = _add_eq(_add_repr(_CountingAttr)) + + +class Factory: + """ + Stores a factory callable. + + If passed as the default value to `attrs.field`, the factory is used to + generate a new value. + + :param callable factory: A callable that takes either none or exactly one + mandatory positional argument depending on *takes_self*. + :param bool takes_self: Pass the partially initialized instance that is + being initialized as a positional argument. + + .. versionadded:: 17.1.0 *takes_self* + """ + + __slots__ = ("factory", "takes_self") + + def __init__(self, factory, takes_self=False): + self.factory = factory + self.takes_self = takes_self + + def __getstate__(self): + """ + Play nice with pickle. + """ + return tuple(getattr(self, name) for name in self.__slots__) + + def __setstate__(self, state): + """ + Play nice with pickle. + """ + for name, value in zip(self.__slots__, state): + setattr(self, name, value) + + +_f = [ + Attribute( + name=name, + default=NOTHING, + validator=None, + repr=True, + cmp=None, + eq=True, + order=False, + hash=True, + init=True, + inherited=False, + ) + for name in Factory.__slots__ +] + +Factory = _add_hash(_add_eq(_add_repr(Factory, attrs=_f), attrs=_f), attrs=_f) + + +def make_class(name, attrs, bases=(object,), **attributes_arguments): + r""" + A quick way to create a new class called *name* with *attrs*. + + :param str name: The name for the new class. + + :param attrs: A list of names or a dictionary of mappings of names to + `attr.ib`\ s / `attrs.field`\ s. + + The order is deduced from the order of the names or attributes inside + *attrs*. Otherwise the order of the definition of the attributes is + used. + :type attrs: `list` or `dict` + + :param tuple bases: Classes that the new class will subclass. + + :param attributes_arguments: Passed unmodified to `attr.s`. + + :return: A new class with *attrs*. + :rtype: type + + .. versionadded:: 17.1.0 *bases* + .. versionchanged:: 18.1.0 If *attrs* is ordered, the order is retained. + """ + if isinstance(attrs, dict): + cls_dict = attrs + elif isinstance(attrs, (list, tuple)): + cls_dict = {a: attrib() for a in attrs} + else: + raise TypeError("attrs argument must be a dict or a list.") + + pre_init = cls_dict.pop("__attrs_pre_init__", None) + post_init = cls_dict.pop("__attrs_post_init__", None) + user_init = cls_dict.pop("__init__", None) + + body = {} + if pre_init is not None: + body["__attrs_pre_init__"] = pre_init + if post_init is not None: + body["__attrs_post_init__"] = post_init + if user_init is not None: + body["__init__"] = user_init + + type_ = types.new_class(name, bases, {}, lambda ns: ns.update(body)) + + # For pickling to work, the __module__ variable needs to be set to the + # frame where the class is created. Bypass this step in environments where + # sys._getframe is not defined (Jython for example) or sys._getframe is not + # defined for arguments greater than 0 (IronPython). + try: + type_.__module__ = sys._getframe(1).f_globals.get( + "__name__", "__main__" + ) + except (AttributeError, ValueError): + pass + + # We do it here for proper warnings with meaningful stacklevel. + cmp = attributes_arguments.pop("cmp", None) + ( + attributes_arguments["eq"], + attributes_arguments["order"], + ) = _determine_attrs_eq_order( + cmp, + attributes_arguments.get("eq"), + attributes_arguments.get("order"), + True, + ) + + return _attrs(these=cls_dict, **attributes_arguments)(type_) + + +# These are required by within this module so we define them here and merely +# import into .validators / .converters. + + +@attrs(slots=True, hash=True) +class _AndValidator: + """ + Compose many validators to a single one. + """ + + _validators = attrib() + + def __call__(self, inst, attr, value): + for v in self._validators: + v(inst, attr, value) + + +def and_(*validators): + """ + A validator that composes multiple validators into one. + + When called on a value, it runs all wrapped validators. + + :param callables validators: Arbitrary number of validators. + + .. versionadded:: 17.1.0 + """ + vals = [] + for validator in validators: + vals.extend( + validator._validators + if isinstance(validator, _AndValidator) + else [validator] + ) + + return _AndValidator(tuple(vals)) + + +def pipe(*converters): + """ + A converter that composes multiple converters into one. + + When called on a value, it runs all wrapped converters, returning the + *last* value. + + Type annotations will be inferred from the wrapped converters', if + they have any. + + :param callables converters: Arbitrary number of converters. + + .. versionadded:: 20.1.0 + """ + + def pipe_converter(val): + for converter in converters: + val = converter(val) + + return val + + if not converters: + # If the converter list is empty, pipe_converter is the identity. + A = typing.TypeVar("A") + pipe_converter.__annotations__ = {"val": A, "return": A} + else: + # Get parameter type from first converter. + t = _AnnotationExtractor(converters[0]).get_first_param_type() + if t: + pipe_converter.__annotations__["val"] = t + + # Get return type from last converter. + rt = _AnnotationExtractor(converters[-1]).get_return_type() + if rt: + pipe_converter.__annotations__["return"] = rt + + return pipe_converter |