_get() - Code Metrics - Inspection of "Cut down on duplication" - mwchase/class-namespaces - Measure and Improve Code Quality continuously with Scrutinizer

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by Max

created 2016-11-20 06:34 UTC

_get() A

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Lines	0
Ratio	0 %

Importance

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Metric	Value
cc	3
c	2
b	0
f	0
dl	0
loc	7
rs	9.4285

"""Class Namespaces (internal module)

All of the guts of the class namespace implementation.

"""


# See https://blog.ionelmc.ro/2015/02/09/understanding-python-metaclasses/

import collections.abc
import functools
import itertools
import sys
import weakref


ENABLE_SET_NAME = sys.version_info >= (3, 6)


_PROXY_INFOS = weakref.WeakKeyDictionary()
_SENTINEL = object()


class _DescriptorInspector(collections.namedtuple('_DescriptorInspector',
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
                                                  ['object', 'dict'])):

    __slots__ = ()

    def __new__(cls, obj):
        dct = collections.ChainMap(*[vars(cls) for cls in type(obj).__mro__])
        return super().__new__(cls, obj, dct)

    @property
    def has_get(self):
        """Return whether self.object's mro provides __get__."""
        return '__get__' in self.dict

    @property
    def has_set(self):
        """Return whether self.object's mro provides __set__."""
        return '__set__' in self.dict

    @property
    def has_delete(self):
        """Return whether self.object's mro provides __delete__."""
        return '__delete__' in self.dict

    if ENABLE_SET_NAME:
        @property
        def has_set_name(self):
            """Return whether self.object's mro provides __set_name__."""
            return '__set_name__' in self.dict

        def set_name(self, owner, name):
            """Call __set_name__, bypassing descriptor protocol."""
            self.get_as_attribute('__set_name__')(self.object, owner, name)

        @property
        def has_non_data(self):
            """Return whether self.object's mro provides non-data methods."""
            return self.has_get or self.has_set_name
    else:
        has_non_data = has_get

    @property
    def is_data(self):
        """Returns whether self.object is a data descriptor."""
        return self.has_set or self.has_delete

    @property
    def is_non_data(self):
        """Returns whether self.object is a non-data descriptor."""
        return self.has_non_data and not self.is_data

    @property
    def is_descriptor(self):
        """Returns whether self.object is a descriptor."""
        return self.has_non_data or self.is_data

    def get_as_attribute(self, key):
        """Return attribute with the given name, or raise AttributeError."""
        try:
            return self.dict[key]
        except KeyError:
            raise AttributeError(key)

    def get(self, instance, owner):
        """Return the result of __get__, bypassing descriptor protocol."""
        return self.get_as_attribute('__get__')(self.object, instance, owner)

    def set(self, instance, value):
        """Call __set__, bypassing descriptor protocol."""
        self.get_as_attribute('__set__')(self.object, instance, value)

    def delete(self, instance):
        """Call __delete__, bypassing descriptor protocol."""
        self.get_as_attribute('__delete__')(self.object, instance)


def _no_blocker(dct, cls):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
    try:
        namespace = vars(cls)
        for name in dct.path:
            namespace = namespace[name]
            if not isinstance(namespace, Namespace):
                return False
    except KeyError:
try:
    raises_exception()
except:  # Could be removed
    pass
        pass
    return True


def _mro_to_chained(mro, dct):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
    mro = (cls for cls in mro if isinstance(cls, Namespaceable))
    mro = itertools.takewhile(functools.partial(_no_blocker, dct), mro)
    mro = (cls for cls in mro if Namespace.namespace_exists(cls, dct.path))
    return collections.ChainMap(
        *[Namespace.get_namespace(cls, dct.path) for cls in mro])


def _instance_map(ns_proxy):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
    dct, instance, _ = _PROXY_INFOS[ns_proxy]
    if instance is not None:
        if isinstance(instance, Namespaceable):
            return _mro_to_chained(instance.__mro__, dct)
        else:
            return Namespace.get_namespace(instance, dct.path)
    else:
        return {}


def _mro_map(ns_proxy):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
    dct, _, owner = _PROXY_INFOS[ns_proxy]
    mro = owner.__mro__
    mro = mro[mro.index(dct.parent_object):]
    return _mro_to_chained(mro, dct)


def _retarget(ns_proxy):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
    dct, instance, owner = _PROXY_INFOS[ns_proxy]
    if instance is None and isinstance(type(owner), Namespaceable):
        instance, owner = owner, type(owner)
        dct = Namespace.get_namespace(owner, dct.path)
        ns_proxy = _NamespaceProxy(dct, instance, owner)
    return ns_proxy


def _get(a_map, name):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
    try:
        value = a_map[name]
    except KeyError:
        return None
    else:
        return _DescriptorInspector(value)


class _NamespaceProxy:

    """Proxy object for manipulating and querying namespaces."""

    __slots__ = '__weakref__',

    def __init__(self, dct, instance, owner):
        _PROXY_INFOS[self] = dct, instance, owner

    def __dir__(self):
        return collections.ChainMap(_instance_map(self), _mro_map(self))

    def __getattribute__(self, name):
        self = _retarget(self)
        dct, instance, owner = _PROXY_INFOS[self]
        if owner is None:
            return dct[name]
        instance_map = _instance_map(self)
        mro_map = _mro_map(self)
        instance_value = _get(instance_map, name)
        mro_value = _get(mro_map, name)
        if issubclass(owner, type):
            if mro_value is not None and mro_value.is_data:
                return mro_value.get(instance, owner)
            elif instance_value is not None and instance_value.has_get:
                return instance_value.get(None, instance)
            elif instance_value is not None:
                return instance_value.object
            elif mro_value is not None and mro_value.has_get:
                return mro_value.get(instance, owner)
            elif mro_value is not None:
                return mro_value.object
            else:
                raise AttributeError(name)
        else:
            if mro_value is not None and mro_value.is_data:
                return mro_value.get(instance, owner)
            elif instance_value is not None:
                return instance_value.object
            elif mro_value is not None and mro_value.has_get:
                return mro_value.get(instance, owner)
            elif mro_value is not None:
                return mro_value.object
            else:
                raise AttributeError(name)

    def __setattr__(self, name, value):
        self = _retarget(self)
        dct, instance, owner = _PROXY_INFOS[self]
        if owner is None:
            dct[name] = value
            return
        if instance is None:
            real_map = Namespace.get_namespace(owner, dct.path)
            real_map[name] = value
            return
        mro_map = _mro_map(self)
        try:
            target_value = mro_map[name]
        except KeyError:
            pass
        else:
            target_value = _DescriptorInspector(target_value)
            if target_value.is_data:
                target_value.set(instance, value)
                return
        instance_map = Namespace.get_namespace(instance, dct.path)
        instance_map[name] = value

    def __delattr__(self, name):
        self = _retarget(self)
        dct, instance, owner = _PROXY_INFOS[self]
        if owner is None:
            del dct[name]
            return
        real_map = Namespace.get_namespace(owner, dct.path)
        if instance is None:
            try:
                del real_map[name]
                return
            except KeyError:
                raise AttributeError(name)
        try:
            value = real_map[name]
        except KeyError:
            pass
        else:
            value = _DescriptorInspector(value)
            if value.is_data:
                value.delete(instance)
                return
        instance_map = Namespace.get_namespace(instance, dct.path)
        try:
            del instance_map[name]
        except KeyError:
            raise AttributeError(name)

    def __enter__(self):
        dct, _, _ = _PROXY_INFOS[self]
        return dct.__enter__()

    def __exit__(self, exc_type, exc_value, traceback):
        dct, _, _ = _PROXY_INFOS[self]
        return dct.__exit__(exc_type, exc_value, traceback)


class Namespace(dict):

    """Namespace."""

    __slots__ = 'name', 'scope', 'parent', 'active', 'parent_object'

    __namespaces = {}

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        bad_values = tuple(
            value for value in self.values() if
            isinstance(value, (Namespace, _NamespaceProxy)))
        if bad_values:
            raise ValueError('Bad values: {}'.format(bad_values))
        self.name = None
        self.scope = None
        self.parent = None
        self.active = False
        self.parent_object = None

    @classmethod
    def premake(cls, name, parent):
        """Return an empty namespace with the given name and parent."""
        self = cls()
        self.name = name
        self.parent = parent
        return self

    def __setitem__(self, key, value):
        if (
                self.parent_object is not None and
                isinstance(value, Namespace) and value.name != key):
            value.push(key, self.scope)
            value.add(self.parent_object)
        super().__setitem__(key, value)

    def __enter__(self):
        self.activate()
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        if self.name is None:
            raise RuntimeError('Namespace must be named.')
        self.deactivate()

    @property
    def path(self):
        """Return the full path of the namespace."""
        if self.name is None or self.parent is None:
            raise ValueError
        if isinstance(self.parent, Namespace):
            parent_path = self.parent.path
        else:
            parent_path = ()
        return parent_path + (self.name,)

    @classmethod
    def __get_helper(cls, target, path):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
        if isinstance(target, Namespaceable):
            path_ = target, path
            namespaces = cls.__namespaces
        else:
            path_ = path
            try:
                namespaces = target.__namespaces
            except AttributeError:
                namespaces = {}
                target.__namespaces = namespaces
        return path_, namespaces

    @classmethod
    def namespace_exists(cls, target, path):
        """Return whether the given namespace exists."""
        path_, namespaces = cls.__get_helper(target, path)
        return path_ in namespaces

    @classmethod
    def get_namespace(cls, target, path):
        """Return a namespace with given target and path, create if needed."""
        path_, namespaces = cls.__get_helper(target, path)
        try:
            return namespaces[path_]
        except KeyError:
            if len(path) == 1:
                parent = {}
            else:
                parent = cls.get_namespace(target, path[:-1])
            return namespaces.setdefault(path_, cls.premake(path[-1], parent))

    def add(self, target):
        """Add self as a namespace under target."""
        path, namespaces = self.__get_helper(target, self.path)
        res = namespaces.setdefault(path, self)
        if res is self:
            self.parent_object = target

    def push(self, name, scope):
        """Bind self to the given name and scope, and activate."""
        if self.name is None:
            self.name = name
        if self.scope is None:
            self.scope = scope
        if self.parent is None:
            self.parent = scope.dicts[-1]
        if name != self.name:
            raise ValueError('Cannot rename namespace')
        if scope is not self.scope:
            raise ValueError('Cannot reuse namespace')
        if scope.dicts[-1] is not self.parent:
            raise ValueError('Cannot reparent namespace')
        self.scope.namespaces.append(self)
        self.activate()

    def activate(self):
        """Take over as the scope for the target."""
        if self.scope is not None and not self.active:
            if self.scope.dicts[-1] is not self.parent:
                raise ValueError('Cannot reparent namespace')
            self.active = True
            self.scope.dicts.append(self)

    def deactivate(self):
        """Stop being the scope for the target."""
        if self.scope is not None and self.active:
            self.active = False
            self.scope.dicts.pop()

    def __get__(self, instance, owner):
        return _NamespaceProxy(self, instance, owner)


class _NamespaceScope(collections.abc.MutableMapping):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""

    __slots__ = 'dicts', 'namespaces'

    def __init__(self):
        self.dicts = [{}]
        self.namespaces = []

    def __getitem__(self, key):
        value = self.dicts[-1][key]
        if isinstance(value, Namespace):
            value = _NamespaceProxy(value, None, None)
        return value

    def __setitem__(self, key, value):
        dct = self.dicts[-1]
        if isinstance(value, _NamespaceProxy):
            value, _, _ = _PROXY_INFOS[value]
        if isinstance(value, Namespace) and value.name != key:
            value.push(key, self)
        dct[key] = value

    def __delitem__(self, key):
        del self.dicts[-1][key]

    def __iter__(self):
        return iter(collections.ChainMap(*self.dicts))

    def __len__(self):
        return len(collections.ChainMap(*self.dicts))


class Namespaceable(type):

    """Metaclass for classes that can contain namespaces."""

    @classmethod
    def __prepare__(mcs, name, bases):

        return _NamespaceScope()

    def __new__(mcs, name, bases, dct):
        cls = super().__new__(mcs, name, bases, dct.dicts[-1])
        cls.__scope = dct
        for namespace in dct.namespaces:
            namespace.add(cls)
            if ENABLE_SET_NAME:
                for name, value in namespace.items():
                    wrapped = _DescriptorInspector(value)
                    if wrapped.has_set_name:
                        wrapped.set_name(cls, name)
        return cls

    def __setattr__(cls, name, value):
        if isinstance(value, Namespace) and value.name != name:
            value.push(name, cls.__scope)
            value.add(cls)
        if issubclass(cls, Namespaceable):
            super().__setattr__(cls, name, value)
        else:
            super().__setattr__(name, value)


1			"""Class Namespaces (internal module)
2
3			All of the guts of the class namespace implementation.
4
5			"""
6
7
8			# See https://blog.ionelmc.ro/2015/02/09/understanding-python-metaclasses/
9
10			import collections.abc
11			import functools
12			import itertools
13			import sys
14			import weakref
15
16
17			ENABLE_SET_NAME = sys.version_info >= (3, 6)
18
19
20			_PROXY_INFOS = weakref.WeakKeyDictionary()
21			_SENTINEL = object()
22
23
24			class _DescriptorInspector(collections.namedtuple('_DescriptorInspector',
			0 ignored issues – show Coding Style introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report This class should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
25			['object', 'dict'])):
26
27			__slots__ = ()
28
29			def __new__(cls, obj):
30			dct = collections.ChainMap(*[vars(cls) for cls in type(obj).__mro__])
31			return super().__new__(cls, obj, dct)
32
33			@property
34			def has_get(self):
35			"""Return whether self.object's mro provides __get__."""
36			return '__get__' in self.dict
37
38			@property
39			def has_set(self):
40			"""Return whether self.object's mro provides __set__."""
41			return '__set__' in self.dict
42
43			@property
44			def has_delete(self):
45			"""Return whether self.object's mro provides __delete__."""
46			return '__delete__' in self.dict
47
48			if ENABLE_SET_NAME:
49			@property
50			def has_set_name(self):
51			"""Return whether self.object's mro provides __set_name__."""
52			return '__set_name__' in self.dict
53
54			def set_name(self, owner, name):
55			"""Call __set_name__, bypassing descriptor protocol."""
56			self.get_as_attribute('__set_name__')(self.object, owner, name)
57
58			@property
59			def has_non_data(self):
60			"""Return whether self.object's mro provides non-data methods."""
61			return self.has_get or self.has_set_name
62			else:
63			has_non_data = has_get
64
65			@property
66			def is_data(self):
67			"""Returns whether self.object is a data descriptor."""
68			return self.has_set or self.has_delete
69
70			@property
71			def is_non_data(self):
72			"""Returns whether self.object is a non-data descriptor."""
73			return self.has_non_data and not self.is_data
74
75			@property
76			def is_descriptor(self):
77			"""Returns whether self.object is a descriptor."""
78			return self.has_non_data or self.is_data
79
80			def get_as_attribute(self, key):
81			"""Return attribute with the given name, or raise AttributeError."""
82			try:
83			return self.dict[key]
84			except KeyError:
85			raise AttributeError(key)
86
87			def get(self, instance, owner):
88			"""Return the result of __get__, bypassing descriptor protocol."""
89			return self.get_as_attribute('__get__')(self.object, instance, owner)
90
91			def set(self, instance, value):
92			"""Call __set__, bypassing descriptor protocol."""
93			self.get_as_attribute('__set__')(self.object, instance, value)
94
95			def delete(self, instance):
96			"""Call __delete__, bypassing descriptor protocol."""
97			self.get_as_attribute('__delete__')(self.object, instance)
98
99
100			def _no_blocker(dct, cls):
			0 ignored issues – show Coding Style introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report This function should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
101			try:
102			namespace = vars(cls)
103			for name in dct.path:
104			namespace = namespace[name]
105			if not isinstance(namespace, Namespace):
106			return False
107			except KeyError:
			1 ignored issue – show Unused Code introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report This except handler seems to be unused and could be removed. Except handlers which only contain `pass` and do not have an `else` clause can usually simply be removed: try: raises_exception() except: # Could be removed pass Loading history...
108			pass
109			return True
110
111
112			def _mro_to_chained(mro, dct):
			0 ignored issues – show Coding Style introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report This function should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
113			mro = (cls for cls in mro if isinstance(cls, Namespaceable))
114			mro = itertools.takewhile(functools.partial(_no_blocker, dct), mro)
115			mro = (cls for cls in mro if Namespace.namespace_exists(cls, dct.path))
116			return collections.ChainMap(
117			*[Namespace.get_namespace(cls, dct.path) for cls in mro])
118
119
120			def _instance_map(ns_proxy):
			0 ignored issues – show Coding Style introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report This function should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
121			dct, instance, _ = _PROXY_INFOS[ns_proxy]
122			if instance is not None:
123			if isinstance(instance, Namespaceable):
124			return _mro_to_chained(instance.__mro__, dct)
125			else:
126			return Namespace.get_namespace(instance, dct.path)
127			else:
128			return {}
129
130
131			def _mro_map(ns_proxy):
			0 ignored issues – show Coding Style introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report This function should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
132			dct, _, owner = _PROXY_INFOS[ns_proxy]
133			mro = owner.__mro__
134			mro = mro[mro.index(dct.parent_object):]
135			return _mro_to_chained(mro, dct)
136
137
138			def _retarget(ns_proxy):
			0 ignored issues – show Coding Style introduced 2016-11-20 05:57 UTC by Report Bug Copy Issue Report This function should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
139			dct, instance, owner = _PROXY_INFOS[ns_proxy]
140			if instance is None and isinstance(type(owner), Namespaceable):
141			instance, owner = owner, type(owner)
142			dct = Namespace.get_namespace(owner, dct.path)
143			ns_proxy = _NamespaceProxy(dct, instance, owner)
144			return ns_proxy
145
146
147			def _get(a_map, name):
			0 ignored issues – show Coding Style introduced 2016-11-20 06:35 UTC by Report Bug Copy Issue Report This function should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
148			try:
149			value = a_map[name]
150			except KeyError:
151			return None
152			else:
153			return _DescriptorInspector(value)
154
155
156			class _NamespaceProxy:
157
158			"""Proxy object for manipulating and querying namespaces."""
159
160			__slots__ = '__weakref__',
161
162			def __init__(self, dct, instance, owner):
163			_PROXY_INFOS[self] = dct, instance, owner
164
165			def __dir__(self):
166			return collections.ChainMap(_instance_map(self), _mro_map(self))
167
168			def __getattribute__(self, name):
169			self = _retarget(self)
170			dct, instance, owner = _PROXY_INFOS[self]
171			if owner is None:
172			return dct[name]
173			instance_map = _instance_map(self)
174			mro_map = _mro_map(self)
175			instance_value = _get(instance_map, name)
176			mro_value = _get(mro_map, name)
177			if issubclass(owner, type):
178			if mro_value is not None and mro_value.is_data:
179			return mro_value.get(instance, owner)
180			elif instance_value is not None and instance_value.has_get:
181			return instance_value.get(None, instance)
182			elif instance_value is not None:
183			return instance_value.object
184			elif mro_value is not None and mro_value.has_get:
185			return mro_value.get(instance, owner)
186			elif mro_value is not None:
187			return mro_value.object
188			else:
189			raise AttributeError(name)
190			else:
191			if mro_value is not None and mro_value.is_data:
192			return mro_value.get(instance, owner)
193			elif instance_value is not None:
194			return instance_value.object
195			elif mro_value is not None and mro_value.has_get:
196			return mro_value.get(instance, owner)
197			elif mro_value is not None:
198			return mro_value.object
199			else:
200			raise AttributeError(name)
201
202			def __setattr__(self, name, value):
203			self = _retarget(self)
204			dct, instance, owner = _PROXY_INFOS[self]
205			if owner is None:
206			dct[name] = value
207			return
208			if instance is None:
209			real_map = Namespace.get_namespace(owner, dct.path)
210			real_map[name] = value
211			return
212			mro_map = _mro_map(self)
213			try:
214			target_value = mro_map[name]
215			except KeyError:
216			pass
217			else:
218			target_value = _DescriptorInspector(target_value)
219			if target_value.is_data:
220			target_value.set(instance, value)
221			return
222			instance_map = Namespace.get_namespace(instance, dct.path)
223			instance_map[name] = value
224
225			def __delattr__(self, name):
226			self = _retarget(self)
227			dct, instance, owner = _PROXY_INFOS[self]
228			if owner is None:
229			del dct[name]
230			return
231			real_map = Namespace.get_namespace(owner, dct.path)
232			if instance is None:
233			try:
234			del real_map[name]
235			return
236			except KeyError:
237			raise AttributeError(name)
238			try:
239			value = real_map[name]
240			except KeyError:
241			pass
242			else:
243			value = _DescriptorInspector(value)
244			if value.is_data:
245			value.delete(instance)
246			return
247			instance_map = Namespace.get_namespace(instance, dct.path)
248			try:
249			del instance_map[name]
250			except KeyError:
251			raise AttributeError(name)
252
253			def __enter__(self):
254			dct, _, _ = _PROXY_INFOS[self]
255			return dct.__enter__()
256
257			def __exit__(self, exc_type, exc_value, traceback):
258			dct, _, _ = _PROXY_INFOS[self]
259			return dct.__exit__(exc_type, exc_value, traceback)
260
261
262			class Namespace(dict):
263
264			"""Namespace."""
265
266			__slots__ = 'name', 'scope', 'parent', 'active', 'parent_object'
267
268			__namespaces = {}
269
270			def __init__(self, args, *kwargs):
271			super().__init__(args, *kwargs)
272			bad_values = tuple(
273			value for value in self.values() if
274			isinstance(value, (Namespace, _NamespaceProxy)))
275			if bad_values:
276			raise ValueError('Bad values: {}'.format(bad_values))
277			self.name = None
278			self.scope = None
279			self.parent = None
280			self.active = False
281			self.parent_object = None
282
283			@classmethod
284			def premake(cls, name, parent):
285			"""Return an empty namespace with the given name and parent."""
286			self = cls()
287			self.name = name
288			self.parent = parent
289			return self
290
291			def __setitem__(self, key, value):
292			if (
293			self.parent_object is not None and
294			isinstance(value, Namespace) and value.name != key):
295			value.push(key, self.scope)
296			value.add(self.parent_object)
297			super().__setitem__(key, value)
298
299			def __enter__(self):
300			self.activate()
301			return self
302
303			def __exit__(self, exc_type, exc_value, traceback):
304			if self.name is None:
305			raise RuntimeError('Namespace must be named.')
306			self.deactivate()
307
308			@property
309			def path(self):
310			"""Return the full path of the namespace."""
311			if self.name is None or self.parent is None:
312			raise ValueError
313			if isinstance(self.parent, Namespace):
314			parent_path = self.parent.path
315			else:
316			parent_path = ()
317			return parent_path + (self.name,)
318
319			@classmethod
320			def __get_helper(cls, target, path):
			0 ignored issues – show Coding Style introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report This method should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
321			if isinstance(target, Namespaceable):
322			path_ = target, path
323			namespaces = cls.__namespaces
324			else:
325			path_ = path
326			try:
327			namespaces = target.__namespaces
328			except AttributeError:
329			namespaces = {}
330			target.__namespaces = namespaces
331			return path_, namespaces
332
333			@classmethod
334			def namespace_exists(cls, target, path):
335			"""Return whether the given namespace exists."""
336			path_, namespaces = cls.__get_helper(target, path)
337			return path_ in namespaces
338
339			@classmethod
340			def get_namespace(cls, target, path):
341			"""Return a namespace with given target and path, create if needed."""
342			path_, namespaces = cls.__get_helper(target, path)
343			try:
344			return namespaces[path_]
345			except KeyError:
346			if len(path) == 1:
347			parent = {}
348			else:
349			parent = cls.get_namespace(target, path[:-1])
350			return namespaces.setdefault(path_, cls.premake(path[-1], parent))
351
352			def add(self, target):
353			"""Add self as a namespace under target."""
354			path, namespaces = self.__get_helper(target, self.path)
355			res = namespaces.setdefault(path, self)
356			if res is self:
357			self.parent_object = target
358
359			def push(self, name, scope):
360			"""Bind self to the given name and scope, and activate."""
361			if self.name is None:
362			self.name = name
363			if self.scope is None:
364			self.scope = scope
365			if self.parent is None:
366			self.parent = scope.dicts[-1]
367			if name != self.name:
368			raise ValueError('Cannot rename namespace')
369			if scope is not self.scope:
370			raise ValueError('Cannot reuse namespace')
371			if scope.dicts[-1] is not self.parent:
372			raise ValueError('Cannot reparent namespace')
373			self.scope.namespaces.append(self)
374			self.activate()
375
376			def activate(self):
377			"""Take over as the scope for the target."""
378			if self.scope is not None and not self.active:
379			if self.scope.dicts[-1] is not self.parent:
380			raise ValueError('Cannot reparent namespace')
381			self.active = True
382			self.scope.dicts.append(self)
383
384			def deactivate(self):
385			"""Stop being the scope for the target."""
386			if self.scope is not None and self.active:
387			self.active = False
388			self.scope.dicts.pop()
389
390			def __get__(self, instance, owner):
391			return _NamespaceProxy(self, instance, owner)
392
393
394			class _NamespaceScope(collections.abc.MutableMapping):
			0 ignored issues – show Coding Style introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report This class should have a docstring. The coding style of this project requires that you add a docstring to this code element. Below, you find an example for methods: class SomeClass: def some_method(self): """Do x and return foo.""" If you would like to know more about docstrings, we recommend to read PEP-257: Docstring Conventions. Loading history...
395
396			__slots__ = 'dicts', 'namespaces'
397
398			def __init__(self):
399			self.dicts = [{}]
400			self.namespaces = []
401
402			def __getitem__(self, key):
403			value = self.dicts[-1][key]
404			if isinstance(value, Namespace):
405			value = _NamespaceProxy(value, None, None)
406			return value
407
408			def __setitem__(self, key, value):
409			dct = self.dicts[-1]
410			if isinstance(value, _NamespaceProxy):
411			value, _, _ = _PROXY_INFOS[value]
412			if isinstance(value, Namespace) and value.name != key:
413			value.push(key, self)
414			dct[key] = value
415
416			def __delitem__(self, key):
417			del self.dicts[-1][key]
418
419			def __iter__(self):
420			return iter(collections.ChainMap(*self.dicts))
421
422			def __len__(self):
423			return len(collections.ChainMap(*self.dicts))
424
425
426			class Namespaceable(type):
427
428			"""Metaclass for classes that can contain namespaces."""
429
430			@classmethod
431			def __prepare__(mcs, name, bases):
			0 ignored issues – show Unused Code introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report The argument `name` seems to be unused. Loading history... Unused Code introduced 2016-11-20 03:53 UTC by Report Bug Copy Issue Report The argument `bases` seems to be unused. Loading history...
432			return _NamespaceScope()
433
434			def __new__(mcs, name, bases, dct):
435			cls = super().__new__(mcs, name, bases, dct.dicts[-1])
436			cls.__scope = dct
437			for namespace in dct.namespaces:
438			namespace.add(cls)
439			if ENABLE_SET_NAME:
440			for name, value in namespace.items():
441			wrapped = _DescriptorInspector(value)
442			if wrapped.has_set_name:
443			wrapped.set_name(cls, name)
444			return cls
445
446			def __setattr__(cls, name, value):
447			if isinstance(value, Namespace) and value.name != name:
448			value.push(name, cls.__scope)
449			value.add(cls)
450			if issubclass(cls, Namespaceable):
451			super().__setattr__(cls, name, value)
452			else:
453			super().__setattr__(name, value)
454

mwchase / class-namespaces

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