_has_get() - Code Metrics - Inspection of "Factor out some complexity." - mwchase/class-namespaces - Measure and Improve Code Quality continuously with Scrutinizer

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by Max

created 2016-11-20 20:20 UTC

_has_get() A

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"""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)


def _has_get(value):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
    return value is not None and value.has_get


def _is_data(value):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
    return value is not None and value.is_data


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 _is_data(mro_value):
            return mro_value.get(instance, owner)
        elif issubclass(owner, type) and _has_get(instance_value):
            return instance_value.get(None, instance)
        elif instance_value is not None:
            return instance_value.object
        elif _has_get(mro_value):
            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:
            try:
                del dct[name]
            except KeyError:
                raise AttributeError(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[0]
        if name != self.name:
            raise ValueError('Cannot rename namespace')
        if scope is not self.scope:
            raise ValueError('Cannot reuse namespace')
        if scope.dicts[0] 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[0] is not self.parent:
                raise ValueError('Cannot reparent namespace')
            self.active = True
            self.scope.dicts.insert(0, 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(0)

    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, dct):
        self.dicts = [dct]
        self.namespaces = []

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

    def __setitem__(self, key, value):
        dct = self.dicts[0]
        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[0][key]

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

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


_NAMESPACE_SCOPES = weakref.WeakKeyDictionary()


class Namespaceable(type):

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

    @classmethod
    def __prepare__(mcs, name, bases, **kwargs):
        return _NamespaceScope(super().__prepare__(name, bases, **kwargs))

    def __new__(mcs, name, bases, dct, **kwargs):
        cls = super().__new__(mcs, name, bases, dct.dicts[0], **kwargs)
        _NAMESPACE_SCOPES[cls] = 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, _NAMESPACE_SCOPES[cls])
            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			def _has_get(value):
			0 ignored issues – show Coding Style introduced 2016-11-20 20:21 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...
157			return value is not None and value.has_get
158
159
160			def _is_data(value):
			0 ignored issues – show Coding Style introduced 2016-11-20 20:21 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...
161			return value is not None and value.is_data
162
163
164			class _NamespaceProxy:
165
166			"""Proxy object for manipulating and querying namespaces."""
167
168			__slots__ = '__weakref__',
169
170			def __init__(self, dct, instance, owner):
171			_PROXY_INFOS[self] = dct, instance, owner
172
173			def __dir__(self):
174			return collections.ChainMap(_instance_map(self), _mro_map(self))
175
176			def __getattribute__(self, name):
177			self = _retarget(self)
178			dct, instance, owner = _PROXY_INFOS[self]
179			if owner is None:
180			return dct[name]
181			instance_map = _instance_map(self)
182			mro_map = _mro_map(self)
183			instance_value = _get(instance_map, name)
184			mro_value = _get(mro_map, name)
185			if _is_data(mro_value):
186			return mro_value.get(instance, owner)
187			elif issubclass(owner, type) and _has_get(instance_value):
188			return instance_value.get(None, instance)
189			elif instance_value is not None:
190			return instance_value.object
191			elif _has_get(mro_value):
192			return mro_value.get(instance, owner)
193			elif mro_value is not None:
194			return mro_value.object
195			else:
196			raise AttributeError(name)
197
198			def __setattr__(self, name, value):
199			self = _retarget(self)
200			dct, instance, owner = _PROXY_INFOS[self]
201			if owner is None:
202			dct[name] = value
203			return
204			if instance is None:
205			real_map = Namespace.get_namespace(owner, dct.path)
206			real_map[name] = value
207			return
208			mro_map = _mro_map(self)
209			try:
210			target_value = mro_map[name]
211			except KeyError:
212			pass
213			else:
214			target_value = _DescriptorInspector(target_value)
215			if target_value.is_data:
216			target_value.set(instance, value)
217			return
218			instance_map = Namespace.get_namespace(instance, dct.path)
219			instance_map[name] = value
220
221			def __delattr__(self, name):
222			self = _retarget(self)
223			dct, instance, owner = _PROXY_INFOS[self]
224			if owner is None:
225			try:
226			del dct[name]
227			except KeyError:
228			raise AttributeError(name)
229			return
230			real_map = Namespace.get_namespace(owner, dct.path)
231			if instance is None:
232			try:
233			del real_map[name]
234			return
235			except KeyError:
236			raise AttributeError(name)
237			try:
238			value = real_map[name]
239			except KeyError:
240			pass
241			else:
242			value = _DescriptorInspector(value)
243			if value.is_data:
244			value.delete(instance)
245			return
246			instance_map = Namespace.get_namespace(instance, dct.path)
247			try:
248			del instance_map[name]
249			except KeyError:
250			raise AttributeError(name)
251
252			def __enter__(self):
253			dct, _, _ = _PROXY_INFOS[self]
254			return dct.__enter__()
255
256			def __exit__(self, exc_type, exc_value, traceback):
257			dct, _, _ = _PROXY_INFOS[self]
258			return dct.__exit__(exc_type, exc_value, traceback)
259
260
261			class Namespace(dict):
262
263			"""Namespace."""
264
265			__slots__ = 'name', 'scope', 'parent', 'active', 'parent_object'
266
267			__namespaces = {}
268
269			def __init__(self, args, *kwargs):
270			super().__init__(args, *kwargs)
271			bad_values = tuple(
272			value for value in self.values() if
273			isinstance(value, (Namespace, _NamespaceProxy)))
274			if bad_values:
275			raise ValueError('Bad values: {}'.format(bad_values))
276			self.name = None
277			self.scope = None
278			self.parent = None
279			self.active = False
280			self.parent_object = None
281
282			@classmethod
283			def premake(cls, name, parent):
284			"""Return an empty namespace with the given name and parent."""
285			self = cls()
286			self.name = name
287			self.parent = parent
288			return self
289
290			def __setitem__(self, key, value):
291			if (
292			self.parent_object is not None and
293			isinstance(value, Namespace) and value.name != key):
294			value.push(key, self.scope)
295			value.add(self.parent_object)
296			super().__setitem__(key, value)
297
298			def __enter__(self):
299			self.activate()
300			return self
301
302			def __exit__(self, exc_type, exc_value, traceback):
303			if self.name is None:
304			raise RuntimeError('Namespace must be named.')
305			self.deactivate()
306
307			@property
308			def path(self):
309			"""Return the full path of the namespace."""
310			if self.name is None or self.parent is None:
311			raise ValueError
312			if isinstance(self.parent, Namespace):
313			parent_path = self.parent.path
314			else:
315			parent_path = ()
316			return parent_path + (self.name,)
317
318			@classmethod
319			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...
320			if isinstance(target, Namespaceable):
321			path_ = target, path
322			namespaces = cls.__namespaces
323			else:
324			path_ = path
325			try:
326			namespaces = target.__namespaces
327			except AttributeError:
328			namespaces = {}
329			target.__namespaces = namespaces
330			return path_, namespaces
331
332			@classmethod
333			def namespace_exists(cls, target, path):
334			"""Return whether the given namespace exists."""
335			path_, namespaces = cls.__get_helper(target, path)
336			return path_ in namespaces
337
338			@classmethod
339			def get_namespace(cls, target, path):
340			"""Return a namespace with given target and path, create if needed."""
341			path_, namespaces = cls.__get_helper(target, path)
342			try:
343			return namespaces[path_]
344			except KeyError:
345			if len(path) == 1:
346			parent = {}
347			else:
348			parent = cls.get_namespace(target, path[:-1])
349			return namespaces.setdefault(path_, cls.premake(path[-1], parent))
350
351			def add(self, target):
352			"""Add self as a namespace under target."""
353			path, namespaces = self.__get_helper(target, self.path)
354			res = namespaces.setdefault(path, self)
355			if res is self:
356			self.parent_object = target
357
358			def push(self, name, scope):
359			"""Bind self to the given name and scope, and activate."""
360			if self.name is None:
361			self.name = name
362			if self.scope is None:
363			self.scope = scope
364			if self.parent is None:
365			self.parent = scope.dicts[0]
366			if name != self.name:
367			raise ValueError('Cannot rename namespace')
368			if scope is not self.scope:
369			raise ValueError('Cannot reuse namespace')
370			if scope.dicts[0] is not self.parent:
371			raise ValueError('Cannot reparent namespace')
372			self.scope.namespaces.append(self)
373			self.activate()
374
375			def activate(self):
376			"""Take over as the scope for the target."""
377			if self.scope is not None and not self.active:
378			if self.scope.dicts[0] is not self.parent:
379			raise ValueError('Cannot reparent namespace')
380			self.active = True
381			self.scope.dicts.insert(0, self)
382
383			def deactivate(self):
384			"""Stop being the scope for the target."""
385			if self.scope is not None and self.active:
386			self.active = False
387			self.scope.dicts.pop(0)
388
389			def __get__(self, instance, owner):
390			return _NamespaceProxy(self, instance, owner)
391
392
393			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...
394
395			__slots__ = 'dicts', 'namespaces'
396
397			def __init__(self, dct):
398			self.dicts = [dct]
399			self.namespaces = []
400
401			def __getitem__(self, key):
402			value = collections.ChainMap(*self.dicts)[key]
403			if isinstance(value, Namespace):
404			value = _NamespaceProxy(value, None, None)
405			return value
406
407			def __setitem__(self, key, value):
408			dct = self.dicts[0]
409			if isinstance(value, _NamespaceProxy):
410			value, _, _ = _PROXY_INFOS[value]
411			if isinstance(value, Namespace) and value.name != key:
412			value.push(key, self)
413			dct[key] = value
414
415			def __delitem__(self, key):
416			del self.dicts[0][key]
417
418			def __iter__(self):
419			return iter(collections.ChainMap(*self.dicts))
420
421			def __len__(self):
422			return len(collections.ChainMap(*self.dicts))
423
424
425			_NAMESPACE_SCOPES = weakref.WeakKeyDictionary()
426
427
428			class Namespaceable(type):
429
430			"""Metaclass for classes that can contain namespaces."""
431
432			@classmethod
433			def __prepare__(mcs, name, bases, **kwargs):
434			return _NamespaceScope(super().__prepare__(name, bases, **kwargs))
435
436			def __new__(mcs, name, bases, dct, **kwargs):
437			cls = super().__new__(mcs, name, bases, dct.dicts[0], **kwargs)
438			_NAMESPACE_SCOPES[cls] = dct
439			for namespace in dct.namespaces:
440			namespace.add(cls)
441			if ENABLE_SET_NAME:
442			for name, value in namespace.items():
443			wrapped = _DescriptorInspector(value)
444			if wrapped.has_set_name:
445			wrapped.set_name(cls, name)
446			return cls
447
448			def __setattr__(cls, name, value):
449			if isinstance(value, Namespace) and value.name != name:
450			value.push(name, _NAMESPACE_SCOPES[cls])
451			value.add(cls)
452			if issubclass(cls, Namespaceable):
453			super().__setattr__(cls, name, value)
454			else:
455			super().__setattr__(name, value)
456

mwchase / class-namespaces

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