--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/thirdparty/attr/_make.py	Sun Oct 01 04:14:16 2017 -0700
@@ -0,0 +1,1059 @@
+from __future__ import absolute_import, division, print_function
+
+import hashlib
+import linecache
+
+from operator import itemgetter
+
+from . import _config
+from ._compat import PY2, iteritems, isclass, iterkeys, metadata_proxy
+from .exceptions import (
+    DefaultAlreadySetError,
+    FrozenInstanceError,
+    NotAnAttrsClassError,
+)
+
+
+# This is used at least twice, so cache it here.
+_obj_setattr = object.__setattr__
+_init_convert_pat = "__attr_convert_{}"
+_init_factory_pat = "__attr_factory_{}"
+_tuple_property_pat = "    {attr_name} = property(itemgetter({index}))"
+_empty_metadata_singleton = metadata_proxy({})
+
+
+class _Nothing(object):
+    """
+    Sentinel class to indicate the lack of a value when ``None`` is ambiguous.
+
+    All instances of `_Nothing` are equal.
+    """
+    def __copy__(self):
+        return self
+
+    def __deepcopy__(self, _):
+        return self
+
+    def __eq__(self, other):
+        return other.__class__ == _Nothing
+
+    def __ne__(self, other):
+        return not self == other
+
+    def __repr__(self):
+        return "NOTHING"
+
+    def __hash__(self):
+        return 0xdeadbeef
+
+
+NOTHING = _Nothing()
+"""
+Sentinel to indicate the lack of a value when ``None`` is ambiguous.
+"""
+
+
+def attr(default=NOTHING, validator=None,
+         repr=True, cmp=True, hash=None, init=True,
+         convert=None, metadata={}):
+    """
+    Create a new attribute on a class.
+
+    ..  warning::
+
+        Does *not* do anything unless the class is also decorated with
+        :func:`attr.s`!
+
+    :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 :class:`Factory`, its callable will be
+        used to construct a new value (useful for mutable datatypes like lists
+        or dicts).
+
+        If a default is not set (or set manually to ``attr.NOTHING``), a value
+        *must* be supplied when instantiating; otherwise a :exc:`TypeError`
+        will be raised.
+
+        The default can also be set using decorator notation as shown below.
+
+    :type default: Any value.
+
+    :param validator: :func:`callable` that is called by ``attrs``-generated
+        ``__init__`` methods after the instance has been initialized.  They
+        receive the initialized instance, the :class:`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
+        :func:`get_run_validators`.
+
+        The validator can also be set using decorator notation as shown below.
+
+    :type validator: ``callable`` or a ``list`` of ``callable``\ s.
+
+    :param bool repr: Include this attribute in the generated ``__repr__``
+        method.
+    :param bool cmp: Include this attribute in the generated comparison methods
+        (``__eq__`` et al).
+    :param hash: Include this attribute in the generated ``__hash__``
+        method.  If ``None`` (default), mirror *cmp*'s value.  This is the
+        correct behavior according the Python spec.  Setting this value to
+        anything else than ``None`` is *discouraged*.
+    :type hash: ``bool`` or ``None``
+    :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 convert: :func:`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 :ref:`extending_metadata`.
+
+    ..  versionchanged:: 17.1.0 *validator* can be a ``list`` now.
+    ..  versionchanged:: 17.1.0
+        *hash* is ``None`` and therefore mirrors *cmp* by default .
+    """
+    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."
+        )
+    return _CountingAttr(
+        default=default,
+        validator=validator,
+        repr=repr,
+        cmp=cmp,
+        hash=hash,
+        init=init,
+        convert=convert,
+        metadata=metadata,
+    )
+
+
+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 = "{}Attributes".format(cls_name)
+    attr_class_template = [
+        "class {}(tuple):".format(attr_class_name),
+        "    __slots__ = ()",
+    ]
+    if attr_names:
+        for i, attr_name in enumerate(attr_names):
+            attr_class_template.append(_tuple_property_pat.format(
+                index=i,
+                attr_name=attr_name,
+            ))
+    else:
+        attr_class_template.append("    pass")
+    globs = {"itemgetter": itemgetter}
+    eval(compile("\n".join(attr_class_template), "", "exec"), globs)
+    return globs[attr_class_name]
+
+
+def _transform_attrs(cls, these):
+    """
+    Transforms all `_CountingAttr`s on a class into `Attribute`s and saves the
+    list in `__attrs_attrs__`.
+
+    If *these* is passed, use that and don't look for them on the class.
+    """
+    super_cls = []
+    for c in reversed(cls.__mro__[1:-1]):
+        sub_attrs = getattr(c, "__attrs_attrs__", None)
+        if sub_attrs is not None:
+            super_cls.extend(a for a in sub_attrs if a not in super_cls)
+    if these is None:
+        ca_list = [(name, attr)
+                   for name, attr
+                   in cls.__dict__.items()
+                   if isinstance(attr, _CountingAttr)]
+    else:
+        ca_list = [(name, ca)
+                   for name, ca
+                   in iteritems(these)]
+
+    non_super_attrs = [
+        Attribute.from_counting_attr(name=attr_name, ca=ca)
+        for attr_name, ca
+        in sorted(ca_list, key=lambda e: e[1].counter)
+    ]
+    attr_names = [a.name for a in super_cls + non_super_attrs]
+
+    AttrsClass = _make_attr_tuple_class(cls.__name__, attr_names)
+
+    cls.__attrs_attrs__ = AttrsClass(super_cls + [
+        Attribute.from_counting_attr(name=attr_name, ca=ca)
+        for attr_name, ca
+        in sorted(ca_list, key=lambda e: e[1].counter)
+    ])
+
+    had_default = False
+    for a in cls.__attrs_attrs__:
+        if these is None and a not in super_cls:
+            setattr(cls, a.name, a)
+        if had_default is True and a.default is NOTHING and a.init is True:
+            raise ValueError(
+                "No mandatory attributes allowed after an attribute with a "
+                "default value or factory.  Attribute in question: {a!r}"
+                .format(a=a)
+            )
+        elif had_default is False and \
+                a.default is not NOTHING and \
+                a.init is not False:
+            had_default = True
+
+
+def _frozen_setattrs(self, name, value):
+    """
+    Attached to frozen classes as __setattr__.
+    """
+    raise FrozenInstanceError()
+
+
+def _frozen_delattrs(self, name):
+    """
+    Attached to frozen classes as __delattr__.
+    """
+    raise FrozenInstanceError()
+
+
+def attributes(maybe_cls=None, these=None, repr_ns=None,
+               repr=True, cmp=True, hash=None, init=True,
+               slots=False, frozen=False, str=False):
+    r"""
+    A class decorator that adds `dunder
+    <https://wiki.python.org/moin/DunderAlias>`_\ -methods according to the
+    specified attributes using :func:`attr.ib` or the *these* argument.
+
+    :param these: A dictionary of name to :func:`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.
+
+    :type these: :class:`dict` of :class:`str` to :func:`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 repr: Create a ``__repr__`` method with a human readable
+        represantation of ``attrs`` attributes..
+    :param bool str: Create a ``__str__`` method that is identical to
+        ``__repr__``.  This is usually not necessary except for
+        :class:`Exception`\ s.
+    :param bool cmp: Create ``__eq__``, ``__ne__``, ``__lt__``, ``__le__``,
+        ``__gt__``, and ``__ge__`` methods that compare the class as if it were
+        a tuple of its ``attrs`` attributes.  But the attributes are *only*
+        compared, if the type of both classes is *identical*!
+    :param hash: If ``None`` (default), the ``__hash__`` method is generated
+        according how *cmp* and *frozen* are set.
+
+        1. If *both* are True, ``attrs`` will generate a ``__hash__`` for you.
+        2. If *cmp* is True and *frozen* is False, ``__hash__`` will be set to
+           None, marking it unhashable (which it is).
+        3. If *cmp* is False, ``__hash__`` will be left untouched meaning the
+           ``__hash__`` method of the superclass will be used (if superclass 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 the `Python documentation \
+        <https://docs.python.org/3/reference/datamodel.html#object.__hash__>`_
+        and the `GitHub issue that led to the default behavior \
+        <https://github.com/python-attrs/attrs/issues/136>`_ for more details.
+    :type hash: ``bool`` or ``None``
+    :param bool init: Create a ``__init__`` method that initialiazes the
+        ``attrs`` attributes.  Leading underscores are stripped for the
+        argument name.  If a ``__attrs_post_init__`` method exists on the
+        class, it will be called after the class is fully initialized.
+    :param bool slots: Create a slots_-style class that's more
+        memory-efficient.  See :ref:`slots` for further ramifications.
+    :param bool frozen: Make instances immutable after initialization.  If
+        someone attempts to modify a frozen instance,
+        :exc:`attr.exceptions.FrozenInstanceError` is raised.
+
+        Please note:
+
+            1. This is achieved by installing a custom ``__setattr__`` method
+               on your class so you can't implement an own one.
+
+            2. True immutability is impossible in Python.
+
+            3. This *does* have a minor a runtime performance :ref:`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)``.
+
+        ..  _slots: https://docs.python.org/3.5/reference/datamodel.html#slots
+
+    ..  versionadded:: 16.0.0 *slots*
+    ..  versionadded:: 16.1.0 *frozen*
+    ..  versionadded:: 16.3.0 *str*, and support for ``__attrs_post_init__``.
+    ..  versionchanged::
+            17.1.0 *hash* supports ``None`` as value which is also the default
+            now.
+    """
+    def wrap(cls):
+        if getattr(cls, "__class__", None) is None:
+            raise TypeError("attrs only works with new-style classes.")
+
+        if repr is False and str is True:
+            raise ValueError(
+                "__str__ can only be generated if a __repr__ exists."
+            )
+
+        if slots:
+            # Only need this later if we're using slots.
+            if these is None:
+                ca_list = [name
+                           for name, attr
+                           in cls.__dict__.items()
+                           if isinstance(attr, _CountingAttr)]
+            else:
+                ca_list = list(iterkeys(these))
+        _transform_attrs(cls, these)
+
+        # Can't just re-use frozen name because Python's scoping. :(
+        # Can't compare function objects because Python 2 is terrible. :(
+        effectively_frozen = _has_frozen_superclass(cls) or frozen
+        if repr is True:
+            cls = _add_repr(cls, ns=repr_ns)
+        if str is True:
+            cls.__str__ = cls.__repr__
+        if cmp is True:
+            cls = _add_cmp(cls)
+
+        if hash is not True and hash is not False and hash is not None:
+            raise TypeError(
+                "Invalid value for hash.  Must be True, False, or None."
+            )
+        elif hash is False or (hash is None and cmp is False):
+            pass
+        elif hash is True or (hash is None and cmp is True and frozen is True):
+            cls = _add_hash(cls)
+        else:
+            cls.__hash__ = None
+
+        if init is True:
+            cls = _add_init(cls, effectively_frozen)
+        if effectively_frozen is True:
+            cls.__setattr__ = _frozen_setattrs
+            cls.__delattr__ = _frozen_delattrs
+            if slots is True:
+                # slots and frozen require __getstate__/__setstate__ to work
+                cls = _add_pickle(cls)
+        if slots is True:
+            cls_dict = dict(cls.__dict__)
+            cls_dict["__slots__"] = tuple(ca_list)
+            for ca_name in ca_list:
+                # It might not actually be in there, e.g. if using 'these'.
+                cls_dict.pop(ca_name, None)
+            cls_dict.pop("__dict__", None)
+
+            qualname = getattr(cls, "__qualname__", None)
+            cls = type(cls)(cls.__name__, cls.__bases__, cls_dict)
+            if qualname is not None:
+                cls.__qualname__ = qualname
+
+        return cls
+
+    # attrs_or class type depends on the usage of the decorator.  It's a class
+    # if it's used as `@attributes` but ``None`` if used # as `@attributes()`.
+    if maybe_cls is None:
+        return wrap
+    else:
+        return wrap(maybe_cls)
+
+
+if PY2:
+    def _has_frozen_superclass(cls):
+        """
+        Check whether *cls* has a frozen ancestor by looking at its
+        __setattr__.
+        """
+        return (
+            getattr(
+                cls.__setattr__, "__module__", None
+            ) == _frozen_setattrs.__module__ and
+            cls.__setattr__.__name__ == _frozen_setattrs.__name__
+        )
+else:
+    def _has_frozen_superclass(cls):
+        """
+        Check whether *cls* has a frozen ancestor by looking at its
+        __setattr__.
+        """
+        return cls.__setattr__ == _frozen_setattrs
+
+
+def _attrs_to_tuple(obj, attrs):
+    """
+    Create a tuple of all values of *obj*'s *attrs*.
+    """
+    return tuple(getattr(obj, a.name) for a in attrs)
+
+
+def _add_hash(cls, attrs=None):
+    """
+    Add a hash method to *cls*.
+    """
+    if attrs is None:
+        attrs = [a
+                 for a in cls.__attrs_attrs__
+                 if a.hash is True or (a.hash is None and a.cmp is True)]
+
+    def hash_(self):
+        """
+        Automatically created by attrs.
+        """
+        return hash(_attrs_to_tuple(self, attrs))
+
+    cls.__hash__ = hash_
+    return cls
+
+
+def _add_cmp(cls, attrs=None):
+    """
+    Add comparison methods to *cls*.
+    """
+    if attrs is None:
+        attrs = [a for a in cls.__attrs_attrs__ if a.cmp]
+
+    def attrs_to_tuple(obj):
+        """
+        Save us some typing.
+        """
+        return _attrs_to_tuple(obj, attrs)
+
+    def eq(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if other.__class__ is self.__class__:
+            return attrs_to_tuple(self) == attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    def ne(self, other):
+        """
+        Automatically created by attrs.
+        """
+        result = eq(self, other)
+        if result is NotImplemented:
+            return NotImplemented
+        else:
+            return not result
+
+    def lt(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if isinstance(other, self.__class__):
+            return attrs_to_tuple(self) < attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    def le(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if isinstance(other, self.__class__):
+            return attrs_to_tuple(self) <= attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    def gt(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if isinstance(other, self.__class__):
+            return attrs_to_tuple(self) > attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    def ge(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if isinstance(other, self.__class__):
+            return attrs_to_tuple(self) >= attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    cls.__eq__ = eq
+    cls.__ne__ = ne
+    cls.__lt__ = lt
+    cls.__le__ = le
+    cls.__gt__ = gt
+    cls.__ge__ = ge
+
+    return cls
+
+
+def _add_repr(cls, ns=None, attrs=None):
+    """
+    Add a repr method to *cls*.
+    """
+    if attrs is None:
+        attrs = [a for a in cls.__attrs_attrs__ if a.repr]
+
+    def repr_(self):
+        """
+        Automatically created by attrs.
+        """
+        real_cls = self.__class__
+        if ns is None:
+            qualname = getattr(real_cls, "__qualname__", None)
+            if qualname is not None:
+                class_name = qualname.rsplit(">.", 1)[-1]
+            else:
+                class_name = real_cls.__name__
+        else:
+            class_name = ns + "." + real_cls.__name__
+
+        return "{0}({1})".format(
+            class_name,
+            ", ".join(a.name + "=" + repr(getattr(self, a.name))
+                      for a in attrs)
+        )
+    cls.__repr__ = repr_
+    return cls
+
+
+def _add_init(cls, frozen):
+    """
+    Add a __init__ method to *cls*.  If *frozen* is True, make it immutable.
+    """
+    attrs = [a for a in cls.__attrs_attrs__
+             if a.init or a.default is not NOTHING]
+
+    # We cache the generated init methods for the same kinds of attributes.
+    sha1 = hashlib.sha1()
+    sha1.update(repr(attrs).encode("utf-8"))
+    unique_filename = "<attrs generated init {0}>".format(
+        sha1.hexdigest()
+    )
+
+    script, globs = _attrs_to_script(
+        attrs,
+        frozen,
+        getattr(cls, "__attrs_post_init__", False),
+    )
+    locs = {}
+    bytecode = compile(script, unique_filename, "exec")
+    attr_dict = dict((a.name, a) for a in attrs)
+    globs.update({
+        "NOTHING": NOTHING,
+        "attr_dict": attr_dict,
+    })
+    if frozen is True:
+        # Save the lookup overhead in __init__ if we need to circumvent
+        # immutability.
+        globs["_cached_setattr"] = _obj_setattr
+    eval(bytecode, globs, locs)
+    init = locs["__init__"]
+
+    # In order of debuggers like PDB being able to step through the code,
+    # we add a fake linecache entry.
+    linecache.cache[unique_filename] = (
+        len(script),
+        None,
+        script.splitlines(True),
+        unique_filename
+    )
+    cls.__init__ = init
+    return cls
+
+
+def _add_pickle(cls):
+    """
+    Add pickle helpers, needed for frozen and slotted classes
+    """
+    def _slots_getstate__(obj):
+        """
+        Play nice with pickle.
+        """
+        return tuple(getattr(obj, a.name) for a in fields(obj.__class__))
+
+    def _slots_setstate__(obj, state):
+        """
+        Play nice with pickle.
+        """
+        __bound_setattr = _obj_setattr.__get__(obj, Attribute)
+        for a, value in zip(fields(obj.__class__), state):
+            __bound_setattr(a.name, value)
+
+    cls.__getstate__ = _slots_getstate__
+    cls.__setstate__ = _slots_setstate__
+    return cls
+
+
+def fields(cls):
+    """
+    Returns 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 attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    :rtype: tuple (with name accesors) of :class:`attr.Attribute`
+
+    ..  versionchanged:: 16.2.0 Returned tuple allows accessing the fields
+        by name.
+    """
+    if not isclass(cls):
+        raise TypeError("Passed object must be a class.")
+    attrs = getattr(cls, "__attrs_attrs__", None)
+    if attrs is None:
+        raise NotAnAttrsClassError(
+            "{cls!r} is not an attrs-decorated class.".format(cls=cls)
+        )
+    return 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 _attrs_to_script(attrs, frozen, post_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 frozen is True:
+        lines.append(
+            # Circumvent the __setattr__ descriptor to save one lookup per
+            # assignment.
+            "_setattr = _cached_setattr.__get__(self, self.__class__)"
+        )
+
+        def fmt_setter(attr_name, value_var):
+            return "_setattr('%(attr_name)s', %(value_var)s)" % {
+                "attr_name": attr_name,
+                "value_var": value_var,
+            }
+
+        def fmt_setter_with_converter(attr_name, value_var):
+            conv_name = _init_convert_pat.format(attr_name)
+            return "_setattr('%(attr_name)s', %(conv)s(%(value_var)s))" % {
+                "attr_name": attr_name,
+                "value_var": value_var,
+                "conv": conv_name,
+            }
+    else:
+        def fmt_setter(attr_name, value):
+            return "self.%(attr_name)s = %(value)s" % {
+                "attr_name": attr_name,
+                "value": value,
+            }
+
+        def fmt_setter_with_converter(attr_name, value_var):
+            conv_name = _init_convert_pat.format(attr_name)
+            return "self.%(attr_name)s = %(conv)s(%(value_var)s)" % {
+                "attr_name": attr_name,
+                "value_var": value_var,
+                "conv": conv_name,
+            }
+
+    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 = {}
+
+    for a in attrs:
+        if a.validator:
+            attrs_to_validate.append(a)
+        attr_name = a.name
+        arg_name = a.name.lstrip("_")
+        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.format(a.name)
+                if a.convert is not None:
+                    lines.append(fmt_setter_with_converter(
+                        attr_name,
+                        init_factory_name + "({0})".format(maybe_self)))
+                    conv_name = _init_convert_pat.format(a.name)
+                    names_for_globals[conv_name] = a.convert
+                else:
+                    lines.append(fmt_setter(
+                        attr_name,
+                        init_factory_name + "({0})".format(maybe_self)
+                    ))
+                names_for_globals[init_factory_name] = a.default.factory
+            else:
+                if a.convert is not None:
+                    lines.append(fmt_setter_with_converter(
+                        attr_name,
+                        "attr_dict['{attr_name}'].default"
+                        .format(attr_name=attr_name)
+                    ))
+                    conv_name = _init_convert_pat.format(a.name)
+                    names_for_globals[conv_name] = a.convert
+                else:
+                    lines.append(fmt_setter(
+                        attr_name,
+                        "attr_dict['{attr_name}'].default"
+                        .format(attr_name=attr_name)
+                    ))
+        elif a.default is not NOTHING and not has_factory:
+            args.append(
+                "{arg_name}=attr_dict['{attr_name}'].default".format(
+                    arg_name=arg_name,
+                    attr_name=attr_name,
+                )
+            )
+            if a.convert is not None:
+                lines.append(fmt_setter_with_converter(attr_name, arg_name))
+                names_for_globals[_init_convert_pat.format(a.name)] = a.convert
+            else:
+                lines.append(fmt_setter(attr_name, arg_name))
+        elif has_factory:
+            args.append("{arg_name}=NOTHING".format(arg_name=arg_name))
+            lines.append("if {arg_name} is not NOTHING:"
+                         .format(arg_name=arg_name))
+            init_factory_name = _init_factory_pat.format(a.name)
+            if a.convert is not None:
+                lines.append("    " + fmt_setter_with_converter(attr_name,
+                                                                arg_name))
+                lines.append("else:")
+                lines.append("    " + fmt_setter_with_converter(
+                    attr_name,
+                    init_factory_name + "({0})".format(maybe_self)
+                ))
+                names_for_globals[_init_convert_pat.format(a.name)] = a.convert
+            else:
+                lines.append("    " + fmt_setter(attr_name, arg_name))
+                lines.append("else:")
+                lines.append("    " + fmt_setter(
+                    attr_name,
+                    init_factory_name + "({0})".format(maybe_self)
+                ))
+            names_for_globals[init_factory_name] = a.default.factory
+        else:
+            args.append(arg_name)
+            if a.convert is not None:
+                lines.append(fmt_setter_with_converter(attr_name, arg_name))
+                names_for_globals[_init_convert_pat.format(a.name)] = a.convert
+            else:
+                lines.append(fmt_setter(attr_name, arg_name))
+
+    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_{}".format(a.name)
+            attr_name = "__attr_{}".format(a.name)
+            lines.append("    {}(self, {}, self.{})".format(
+                val_name, attr_name, a.name))
+            names_for_globals[val_name] = a.validator
+            names_for_globals[attr_name] = a
+    if post_init:
+        lines.append("self.__attrs_post_init__()")
+
+    return """\
+def __init__(self, {args}):
+    {lines}
+""".format(
+        args=", ".join(args),
+        lines="\n    ".join(lines) if lines else "pass",
+    ), names_for_globals
+
+
+class Attribute(object):
+    """
+    *Read-only* representation of an attribute.
+
+    :attribute name: The name of the attribute.
+
+    Plus *all* arguments of :func:`attr.ib`.
+    """
+    __slots__ = (
+        "name", "default", "validator", "repr", "cmp", "hash", "init",
+        "convert", "metadata",
+    )
+
+    def __init__(self, name, default, validator, repr, cmp, hash, init,
+                 convert=None, metadata=None):
+        # Cache this descriptor here to speed things up later.
+        bound_setattr = _obj_setattr.__get__(self, Attribute)
+
+        bound_setattr("name", name)
+        bound_setattr("default", default)
+        bound_setattr("validator", validator)
+        bound_setattr("repr", repr)
+        bound_setattr("cmp", cmp)
+        bound_setattr("hash", hash)
+        bound_setattr("init", init)
+        bound_setattr("convert", convert)
+        bound_setattr("metadata", (metadata_proxy(metadata) if metadata
+                                   else _empty_metadata_singleton))
+
+    def __setattr__(self, name, value):
+        raise FrozenInstanceError()
+
+    @classmethod
+    def from_counting_attr(cls, name, ca):
+        inst_dict = {
+            k: getattr(ca, k)
+            for k
+            in Attribute.__slots__
+            if k not in (
+                "name", "validator", "default",
+            )  # exclude methods
+        }
+        return cls(name=name, validator=ca._validator, default=ca._default,
+                   **inst_dict)
+
+    # 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.
+        """
+        bound_setattr = _obj_setattr.__get__(self, Attribute)
+        for name, value in zip(self.__slots__, state):
+            if name != "metadata":
+                bound_setattr(name, value)
+            else:
+                bound_setattr(name, metadata_proxy(value) if value else
+                              _empty_metadata_singleton)
+
+
+_a = [Attribute(name=name, default=NOTHING, validator=None,
+                repr=True, cmp=True, hash=(name != "metadata"), init=True)
+      for name in Attribute.__slots__]
+
+Attribute = _add_hash(
+    _add_cmp(_add_repr(Attribute, attrs=_a), attrs=_a),
+    attrs=[a for a in _a if a.hash]
+)
+
+
+class _CountingAttr(object):
+    """
+    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", "cmp", "hash", "init",
+                 "metadata", "_validator", "convert")
+    __attrs_attrs__ = tuple(
+        Attribute(name=name, default=NOTHING, validator=None,
+                  repr=True, cmp=True, hash=True, init=True)
+        for name
+        in ("counter", "_default", "repr", "cmp", "hash", "init",)
+    ) + (
+        Attribute(name="metadata", default=None, validator=None,
+                  repr=True, cmp=True, hash=False, init=True),
+    )
+    cls_counter = 0
+
+    def __init__(self, default, validator, repr, cmp, hash, init, convert,
+                 metadata):
+        _CountingAttr.cls_counter += 1
+        self.counter = _CountingAttr.cls_counter
+        self._default = default
+        # If validator is a list/tuple, wrap it using helper validator.
+        if validator and isinstance(validator, (list, tuple)):
+            self._validator = and_(*validator)
+        else:
+            self._validator = validator
+        self.repr = repr
+        self.cmp = cmp
+        self.hash = hash
+        self.init = init
+        self.convert = convert
+        self.metadata = metadata
+
+    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_cmp(_add_repr(_CountingAttr))
+
+
+@attributes(slots=True, init=False)
+class Factory(object):
+    """
+    Stores a factory callable.
+
+    If passed as the default value to :func:`attr.ib`, 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*
+    """
+    factory = attr()
+    takes_self = attr()
+
+    def __init__(self, factory, takes_self=False):
+        """
+        `Factory` is part of the default machinery so if we want a default
+        value here, we have to implement it ourselves.
+        """
+        self.factory = factory
+        self.takes_self = takes_self
+
+
+def make_class(name, attrs, bases=(object,), **attributes_arguments):
+    """
+    A quick way to create a new class called *name* with *attrs*.
+
+    :param name: The name for the new class.
+    :type name: str
+
+    :param attrs: A list of names or a dictionary of mappings of names to
+        attributes.
+    :type attrs: :class:`list` or :class:`dict`
+
+    :param tuple bases: Classes that the new class will subclass.
+
+    :param attributes_arguments: Passed unmodified to :func:`attr.s`.
+
+    :return: A new class with *attrs*.
+    :rtype: type
+
+    ..  versionadded:: 17.1.0 *bases*
+    """
+    if isinstance(attrs, dict):
+        cls_dict = attrs
+    elif isinstance(attrs, (list, tuple)):
+        cls_dict = dict((a, attr()) for a in attrs)
+    else:
+        raise TypeError("attrs argument must be a dict or a list.")
+
+    return attributes(**attributes_arguments)(type(name, bases, cls_dict))
+
+
+# These are required by whithin this module so we define them here and merely
+# import into .validators.
+
+
+@attributes(slots=True, hash=True)
+class _AndValidator(object):
+    """
+    Compose many validators to a single one.
+    """
+    _validators = attr()
+
+    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 validators: Arbitrary number of validators.
+    :type validators: callables
+
+    .. versionadded:: 17.1.0
+    """
+    vals = []
+    for validator in validators:
+        vals.extend(
+            validator._validators if isinstance(validator, _AndValidator)
+            else [validator]
+        )
+
+    return _AndValidator(tuple(vals))