dataclasses - pydoc - phpman

Help on module dataclasses:

NAME
    dataclasses

MODULE REFERENCE
    https://docs.python.org/3.10/library/dataclasses.html

    The following documentation is automatically generated from the Python
    source files.  It may be incomplete, incorrect or include features that
    are considered implementation detail and may vary between Python
    implementations.  When in doubt, consult the module reference at the
    location listed above.

CLASSES
    builtins.AttributeError(builtins.Exception)
        FrozenInstanceError
    builtins.object
        Field
        InitVar

    class Field(builtins.object)
     |  Field(default, default_factory, init, repr, hash, compare, metadata, kw_only)
     |
     |  # Instances of Field are only ever created from within this module,
     |  # and only from the field() function, although Field instances are
     |  # exposed externally as (conceptually) read-only objects.
     |  #
     |  # name and type are filled in after the fact, not in __init__.
     |  # They're not known at the time this class is instantiated, but it's
     |  # convenient if they're available later.
     |  #
     |  # When cls._FIELDS is filled in with a list of Field objects, the name
     |  # and type fields will have been populated.
     |
     |  Methods defined here:
     |
     |  __init__(self, default, default_factory, init, repr, hash, compare, metadata, kw_only)
     |      Initialize self.  See help(type(self)) for accurate signature.
     |
     |  __repr__(self)
     |      Return repr(self).
     |
     |  __set_name__(self, owner, name)
     |      # This is used to support the PEP 487 __set_name__ protocol in the
     |      # case where we're using a field that contains a descriptor as a
     |      # default value.  For details on __set_name__, see
     |      # https://www.python.org/dev/peps/pep-0487/#implementation-details.
     |      #
     |      # Note that in _process_class, this Field object is overwritten
     |      # with the default value, so the end result is a descriptor that
     |      # had __set_name__ called on it at the right time.
     |
     |  ----------------------------------------------------------------------
     |  Class methods defined here:
     |
     |  __class_getitem__ = GenericAlias(...) from builtins.type
     |      Represent a PEP 585 generic type
     |
     |      E.g. for t = list[int], t.__origin__ is list and t.__args__ is (int,).
     |
     |  ----------------------------------------------------------------------
     |  Data descriptors defined here:
     |
     |  compare
     |
     |  default
     |
     |  default_factory
     |
     |  hash
     |
     |  init
     |
     |  kw_only
     |
     |  metadata
     |
     |  name
     |
     |  repr
     |
     |  type

    class FrozenInstanceError(builtins.AttributeError)
     |  # Raised when an attempt is made to modify a frozen class.
     |
     |  Method resolution order:
     |      FrozenInstanceError
     |      builtins.AttributeError
     |      builtins.Exception
     |      builtins.BaseException
     |      builtins.object
     |
     |  Data descriptors defined here:
     |
     |  __weakref__
     |      list of weak references to the object (if defined)
     |
     |  ----------------------------------------------------------------------
     |  Methods inherited from builtins.AttributeError:
     |
     |  __init__(self, /, *args, **kwargs)
     |      Initialize self.  See help(type(self)) for accurate signature.
     |
     |  __str__(self, /)
     |      Return str(self).
     |
     |  ----------------------------------------------------------------------
     |  Data descriptors inherited from builtins.AttributeError:
     |
     |  name
     |      attribute name
     |
     |  obj
     |      object
     |
     |  ----------------------------------------------------------------------
     |  Static methods inherited from builtins.Exception:
     |
     |  __new__(*args, **kwargs) from builtins.type
     |      Create and return a new object.  See help(type) for accurate signature.
     |
     |  ----------------------------------------------------------------------
     |  Methods inherited from builtins.BaseException:
     |
     |  __delattr__(self, name, /)
     |      Implement delattr(self, name).
     |
     |  __getattribute__(self, name, /)
     |      Return getattr(self, name).
     |
     |  __reduce__(...)
     |      Helper for pickle.
     |
     |  __repr__(self, /)
     |      Return repr(self).
     |
     |  __setattr__(self, name, value, /)
     |      Implement setattr(self, name, value).
     |
     |  __setstate__(...)
     |
     |  with_traceback(...)
     |      Exception.with_traceback(tb) --
     |      set self.__traceback__ to tb and return self.
     |
     |  ----------------------------------------------------------------------
     |  Data descriptors inherited from builtins.BaseException:
     |
     |  __cause__
     |      exception cause
     |
     |  __context__
     |      exception context
     |
     |  __dict__
     |
     |  __suppress_context__
     |
     |  __traceback__
     |
     |  args

    class InitVar(builtins.object)
     |  InitVar(type)
     |
     |  Methods defined here:
     |
     |  __init__(self, type)
     |      Initialize self.  See help(type(self)) for accurate signature.
     |
     |  __repr__(self)
     |      Return repr(self).
     |
     |  ----------------------------------------------------------------------
     |  Class methods defined here:
     |
     |  __class_getitem__(type) from builtins.type
     |
     |  ----------------------------------------------------------------------
     |  Data descriptors defined here:
     |
     |  type

FUNCTIONS
    asdict(obj, *, dict_factory=<class 'dict'>)
        Return the fields of a dataclass instance as a new dictionary mapping
        field names to field values.

        Example usage:

          @dataclass
          class C:
              x: int
              y: int

          c = C(1, 2)
          assert asdict(c) == {'x': 1, 'y': 2}

        If given, 'dict_factory' will be used instead of built-in dict.
        The function applies recursively to field values that are
        dataclass instances. This will also look into built-in containers:
        tuples, lists, and dicts.

    astuple(obj, *, tuple_factory=<class 'tuple'>)
        Return the fields of a dataclass instance as a new tuple of field values.

        Example usage::

          @dataclass
          class C:
              x: int
              y: int

        c = C(1, 2)
        assert astuple(c) == (1, 2)

        If given, 'tuple_factory' will be used instead of built-in tuple.
        The function applies recursively to field values that are
        dataclass instances. This will also look into built-in containers:
        tuples, lists, and dicts.

    dataclass(cls=None, /, *, init=True, repr=True, eq=True, order=False, unsafe_hash=False, frozen=False, match_args=True, kw_only=False, slots=False)
        Returns the same class as was passed in, with dunder methods
        added based on the fields defined in the class.

        Examines PEP 526 __annotations__ to determine fields.

        If init is true, an __init__() method is added to the class. If
        repr is true, a __repr__() method is added. If order is true, rich
        comparison dunder methods are added. If unsafe_hash is true, a
        __hash__() method function is added. If frozen is true, fields may
        not be assigned to after instance creation. If match_args is true,
        the __match_args__ tuple is added. If kw_only is true, then by
        default all fields are keyword-only. If slots is true, an
        __slots__ attribute is added.

    field(*, default=<dataclasses._MISSING_TYPE object at 0x7f708881ebc0>, default_factory=<dataclasses._MISSING_TYPE object at 0x7f708881ebc0>, init=True, repr=True, hash=None, compare=True, metadata=None, kw_only=<dataclasses._MISSING_TYPE object at 0x7f708881ebc0>)
        Return an object to identify dataclass fields.

        default is the default value of the field.  default_factory is a
        0-argument function called to initialize a field's value.  If init
        is true, the field will be a parameter to the class's __init__()
        function.  If repr is true, the field will be included in the
        object's repr().  If hash is true, the field will be included in the
        object's hash().  If compare is true, the field will be used in
        comparison functions.  metadata, if specified, must be a mapping
        which is stored but not otherwise examined by dataclass.  If kw_only
        is true, the field will become a keyword-only parameter to
        __init__().

        It is an error to specify both default and default_factory.

    fields(class_or_instance)
        Return a tuple describing the fields of this dataclass.

        Accepts a dataclass or an instance of one. Tuple elements are of
        type Field.

    is_dataclass(obj)
        Returns True if obj is a dataclass or an instance of a
        dataclass.

    make_dataclass(cls_name, fields, *, bases=(), namespace=None, init=True, repr=True, eq=True, order=False, unsafe_hash=False, frozen=False, match_args=True, kw_only=False, slots=False)
        Return a new dynamically created dataclass.

        The dataclass name will be 'cls_name'.  'fields' is an iterable
        of either (name), (name, type) or (name, type, Field) objects. If type is
        omitted, use the string 'typing.Any'.  Field objects are created by
        the equivalent of calling 'field(name, type [, Field-info])'.

          C = make_dataclass('C', ['x', ('y', int), ('z', int, field(init=False))], bases=(Base,))

        is equivalent to:

          @dataclass
          class C(Base):
              x: 'typing.Any'
              y: int
              z: int = field(init=False)

        For the bases and namespace parameters, see the builtin type() function.

        The parameters init, repr, eq, order, unsafe_hash, and frozen are passed to
        dataclass().

    replace(obj, /, **changes)
        Return a new object replacing specified fields with new values.

        This is especially useful for frozen classes.  Example usage:

          @dataclass(frozen=True)
          class C:
              x: int
              y: int

          c = C(1, 2)
          c1 = replace(c, x=3)
          assert c1.x == 3 and c1.y == 2

DATA
    KW_ONLY = <dataclasses._KW_ONLY_TYPE object>
    MISSING = <dataclasses._MISSING_TYPE object>
    __all__ = ['dataclass', 'field', 'Field', 'FrozenInstanceError', 'Init...

FILE
    /usr/lib/python3.10/dataclasses.py