Namespace.total_length() - Code Metrics - Inspection of "Test length of scope." - mwchase/class-namespaces - Measure and Improve Code Quality continuously with Scrutinizer

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Push — master ( 674003...330127 )

by Max

created 2016-11-27 23:27 UTC

Namespace.total_length() A

↳ Parent: Project

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Lines	0
Ratio	0 %

Code Coverage

Tests	1
CRAP Score	4.125

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Metric	Value
cc	3
dl	0
loc	4
ccs	1
cts	2
cp	0.5
crap	4.125
rs	10
c	0
b	0
f	0

"""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 weakref

from . import ops
from .descriptor_inspector import _DescriptorInspector
from .flags import ENABLE_SET_NAME
from .proxy import _Proxy
from .scope_proxy import _ScopeProxy


_PROXY_INFOS = weakref.WeakKeyDictionary()


def _mro_to_chained(mro, path):
    """Return a chained map of lookups for the given namespace and mro."""
    return collections.ChainMap(*[
        Namespace.get_namespace(cls, path) for cls in
        itertools.takewhile(
            functools.partial(Namespace.no_blocker, path),
            (cls for cls in mro if isinstance(cls, _Namespaceable))) if
        Namespace.namespace_exists(path, cls)])


def _instance_map(ns_proxy):
    """Return a map, possibly chained, of lookups for the given instance."""
    dct, instance, _ = _PROXY_INFOS[ns_proxy]
    if instance is not None:
        if isinstance(instance, _Namespaceable):
            return _mro_to_chained(instance.__mro__, dct.path)
        else:
            return Namespace.get_namespace(instance, dct.path)
    else:
        return {}


def _mro_map(ns_proxy):
    """Return a chained map of lookups for the given owner class."""
    dct, _, owner = _PROXY_INFOS[ns_proxy]
    mro = owner.__mro__
    parent_object = dct.parent_object
    index = mro.index(parent_object)
    mro = mro[index:]
    return _mro_to_chained(mro, dct.path)


def _retarget(ns_proxy):
    """Convert a class lookup to an instance lookup, if needed."""
    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


class _NamespaceProxy(_Proxy):

    """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)
        _, instance, owner = _PROXY_INFOS[self]
        instance_map = _instance_map(self)
        mro_map = _mro_map(self)
        instance_value = ops.get(instance_map, name)
        mro_value = ops.get(mro_map, name)
        if ops.is_data(mro_value):
            return mro_value.get(instance, owner)
        elif issubclass(owner, type) and ops.has_get(instance_value):
            return instance_value.get(None, instance)
        elif instance_value is not None:
            return instance_value.object
        elif ops.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 instance is None:
            real_map = Namespace.get_namespace(owner, dct.path)
            real_map[name] = value
            return
        mro_map = _mro_map(self)
        target_value = ops.get_data(mro_map, name)
        if target_value is not None:
            # These lines will be called on a data descriptor.
            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]
        real_map = Namespace.get_namespace(owner, dct.path)
        if instance is None:
            ops.delete(real_map, name)
            return
        value = ops.get_data(real_map, name)
        if value is not None:
            # These lines will be called on a data descriptor.
            value.delete(instance)
            return
        instance_map = Namespace.get_namespace(instance, dct.path)
        ops.delete(instance_map, name)


_NAMESPACE_INFOS = weakref.WeakKeyDictionary()


class Namespace(dict):

    """Namespace."""

    __slots__ = (
        'name', 'scope', 'parent', 'active', 'parent_object', 'needs_setup')

    __namespaces = {}

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        bad_values = tuple(
            value for value in self.values() if
            isinstance(value, (Namespace, _Proxy)))
        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
        self.needs_setup = False

    @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

    # Hold up. Do we need a symmetric addon to __delitem__?
    # I forget how this works.
    def __setitem__(self, key, value):
        if (
                self.scope is not None and
                isinstance(value, self.scope.scope_proxy)):
            value = self.scope.proxies[value]
        if isinstance(value, (_ScopeProxy, _NamespaceProxy)):
            raise ValueError('Cannot move scopes between classes.')
        if isinstance(value, Namespace):
            value.push(key, self.scope, self)
            value.add(self.parent_object)
        super().__setitem__(key, value)

    def __enter__(self):
        self.needs_setup = True
        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:
            # This line can be hit by Namespace().path.
            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):
        """Return the namespace for `target` at `path`, create if needed."""
        if isinstance(target, _Namespaceable):
            path_ = target, path
            namespaces = cls.__namespaces
        else:
            path_ = path
            try:
                namespaces = _NAMESPACE_INFOS[target]
            except KeyError:
                namespaces = {}
                _NAMESPACE_INFOS[target] = namespaces
        return path_, namespaces

    @classmethod
    def namespace_exists(cls, path, target):
        """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))

    @classmethod
    def no_blocker(cls, path, cls_):
        """Return False if there's a non-Namespace object in the path."""
        try:
            namespace = vars(cls_)
            for name in path:
                namespace = namespace[name]
                if not isinstance(namespace, cls):
                    return False
        except KeyError:
try:
    raises_exception()
except:  # Could be removed
    pass
            pass
        return True

    def add(self, target):
        """Add self as a namespace under target."""
        if target is not None:
            path, namespaces = self.__get_helper(target, self.path)
            res = namespaces.setdefault(path, self)
            if res is self:
                self.parent_object = target

    def set_if_none(self, name, value):
        """Set the attribute `name` to `value`, if it's initially None."""
        if getattr(self, name) is None:
            setattr(self, name, value)

    def validate_assignment(self, name, scope):
        """Confirm the instance can be assigned to the given name and scope."""
        if name != self.name:
            raise ValueError('Cannot rename namespace')
        if scope is not self.scope:
            # It should be possible to hit this line by assigning a namespace
            # into another class. It may not be, however.
            raise ValueError('Cannot reuse namespace')

    def validate_parent(self, parent):
        """Confirm that the instance has the correct parent dict."""
        if parent is not self.parent:
            # This line can be hit by assigning a namespace into another
            # namespace.
            raise ValueError('Cannot reparent namespace')

    def push(self, name, scope, parent):
        """Bind self to the given name and scope, and activate."""
        self.set_if_none('name', name)
        self.set_if_none('scope', scope)
        self.set_if_none('parent', parent)
        self.validate_assignment(name, scope)
        self.validate_parent(parent)
        self.scope.namespaces.append(self)
        if self.needs_setup:
            self.activate()

    def activate(self):
        """Take over as the scope for the target."""
        if self.active:
            raise ValueError('Cannot double-activate.')
        if self.scope is not None:
            self.validate_parent(self.scope.head)
            self.active = True
            self.scope.push(self)
            self.needs_setup = False

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

    def total_length(self):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
        return len(self) + sum(
            ns.total_length() for ns in self.values() if
            isinstance(ns, Namespace))

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

    def __bool__(self):
class Foo:
    def some_method(self, x, y):
        return x + y;
        return True


class _NamespaceScope(collections.abc.MutableMapping):

    """The class creation namespace for _Namespaceables."""

    __slots__ = '_dicts', 'namespaces', 'proxies', 'scope_proxy', 'finalized'

    def __init__(self, dct):
        self._dicts = [dct]
        self.namespaces = []
        self.proxies = proxies = weakref.WeakKeyDictionary()
        self.finalized = False

        class ScopeProxy(_ScopeProxy):

            """Local version of ScopeProxy for this scope."""

            __slots__ = ()

            def __init__(self, dct):
                super().__init__(dct, proxies)

        self.scope_proxy = ScopeProxy

    # Mapping methods need to know about the dot syntax.
    # Possibly namespaces themselves should know. Would simplify some things.

    @property
    def head(self):
        """The innermost Namespace scope."""
        return self._dicts[0]

    def finalize(self):
        """Mark the scope as no longer active, and return the head."""
        if len(self._dicts) != 1:
            raise ValueError('Cannot finalize a pushed scope!')
        self.finalized = True
        return self.head

    def push(self, dct):
        """Add a new active Namespace to the scope."""
        if self.finalized:
            raise ValueError('Cannot push a finalized scope!')
        self._dicts.insert(0, dct)

    def pop_(self):
        """Remove the current active Namespace from the scope."""
        if len(self._dicts) == 1:
            raise ValueError('Cannot pop from a basal scope!')
        self._dicts.pop(0)

    def __getitem__(self, key):
        value = collections.ChainMap(*self._dicts)[key]
        if isinstance(value, Namespace):
            value = self.scope_proxy(value)
        return value

    def _store(self, key, value, dct):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
        # We just entered the context successfully.
        if value is dct:
            dct = self._dicts[1]
        if isinstance(value, Namespace):
            value.push(key, self, dct)
        if isinstance(value, self.scope_proxy):
            value = self.proxies[value]
            value.validate_parent(dct)
            value.validate_assignment(key, self)
        return value, dct

    def __setitem__(self, key, value):
        dct = self.head
        value, dct = self._store(key, value, dct)
        if isinstance(value, (_ScopeProxy, _NamespaceProxy)):
            raise ValueError('Cannot move scopes between classes.')
        dct[key] = value

    def __delitem__(self, key):
        del self.head[key]

    # These functions are incorrect and need to be rewritten.
    def __iter__(self):
        if not self.finalized:
            raise ValueError('Iteration not defined on unfinalized scope.')

    def __len__(self):
        if not self.finalized:
            raise ValueError('Length not defined on unfinalized scope.')
        return len(self.head) + sum(
            self.proxies[ns].total_length() for ns in self.head.values() if
            isinstance(ns, self.scope_proxy))


_NAMESPACE_SCOPES = weakref.WeakKeyDictionary()


class _NamespaceBase:

    """Common base class for Namespaceable and its metaclass."""

    __slots__ = ()

    # Note: the dot format of invocation can "escape" self into other objects.
    # This is not intended behavior, and the result of using dots "too deeply"
    # should be considered undefined.
    # I would like it to be an error, if I can figure out how.

    @staticmethod
    def __is_proxy(value):
class SomeClass:
    def some_method(self):
        """Do x and return foo."""
        if not isinstance(value, _NamespaceProxy):
            # This line can be hit by doing what the error message says.
            raise ValueError('Given a dot attribute that went too deep.')
        return value

    def __getattribute__(self, name):
        parent, is_namespace, name_ = name.rpartition('.')
        if is_namespace:
            self_ = self
            for element in parent.split('.'):
                self_ = self.__is_proxy(getattr(self_, element))
            return getattr(getattr(self, parent), name_)
        return super(_NamespaceBase, type(self)).__getattribute__(self, name)

    def __setattr__(self, name, value):
        parent, is_namespace, name_ = name.rpartition('.')
        if is_namespace:
            setattr(self.__is_proxy(getattr(self, parent)), name_, value)
            return
        super(_NamespaceBase, type(self)).__setattr__(self, name, value)

    def __delattr__(self, name):
        parent, is_namespace, name_ = name.rpartition('.')
        if is_namespace:
            delattr(self.__is_proxy(getattr(self, parent)), name_)
            return
        # This line can be hit by deleting an attribute that isn't a namespace.
        super(_NamespaceBase, type(self)).__delattr__(self, name)


class _Namespaceable(_NamespaceBase, type):

    """Metaclass for classes that can contain namespaces.

    Using the metaclass directly is a bad idea. Use a base class instead.
    """

    @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.finalize(), **kwargs)
        if _DEFINED and not issubclass(cls, Namespaceable):
            # This line can be hit with class(metaclass=type(Namespaceable)):
            raise ValueError(
                'Cannot create a _Namespaceable that does not inherit from '
                'Namespaceable')
        _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 (
                '.' not in name and isinstance(value, Namespace) and
                value.name != name):
            scope = _NAMESPACE_SCOPES[cls]
            value.push(name, scope, scope.head)
            value.add(cls)
        super(_Namespaceable, type(cls)).__setattr__(cls, name, value)


_DEFINED = False


class Namespaceable(_NamespaceBase, metaclass=_Namespaceable):

    """Base class for classes that can contain namespaces.

    A note for people extending the functionality:
    The base class for Namespaceable and its metaclass uses a non-standard
    super() invocation in its definitions of several methods. This was the only
    way I could find to mitigate some bugs I encountered with a standard
    invocation. If you override any of methods defined on built-in types, I
    recommend this form for maximal reusability:

    super(class, type(self)).__method__(self, ...)

    This avoids confusing error messages in case self is a subclass of class,
    in addition to being an instance.

    If you're not delegating above Namespaceable, you can probably use the
    standard invocation, unless you bring about the above situation on your own
    types.
    """


_DEFINED = True


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	6	import collections.abc
11	6	import functools
12	6	import itertools
13	6	import weakref
14
15	6	from . import ops
16	6	from .descriptor_inspector import _DescriptorInspector
17	6	from .flags import ENABLE_SET_NAME
18	6	from .proxy import _Proxy
19	6	from .scope_proxy import _ScopeProxy
20
21
22	6	_PROXY_INFOS = weakref.WeakKeyDictionary()
23
24
25	6	def _mro_to_chained(mro, path):
26		"""Return a chained map of lookups for the given namespace and mro."""
27	6	return collections.ChainMap(*[
28		Namespace.get_namespace(cls, path) for cls in
29		itertools.takewhile(
30		functools.partial(Namespace.no_blocker, path),
31		(cls for cls in mro if isinstance(cls, _Namespaceable))) if
32		Namespace.namespace_exists(path, cls)])
33
34
35	6	def _instance_map(ns_proxy):
36		"""Return a map, possibly chained, of lookups for the given instance."""
37	6	dct, instance, _ = _PROXY_INFOS[ns_proxy]
38	6	if instance is not None:
39	6	if isinstance(instance, _Namespaceable):
40	6	return _mro_to_chained(instance.__mro__, dct.path)
41		else:
42	6	return Namespace.get_namespace(instance, dct.path)
43		else:
44	6	return {}
45
46
47	6	def _mro_map(ns_proxy):
48		"""Return a chained map of lookups for the given owner class."""
49	6	dct, _, owner = _PROXY_INFOS[ns_proxy]
50	6	mro = owner.__mro__
51	6	parent_object = dct.parent_object
52	6	index = mro.index(parent_object)
53	6	mro = mro[index:]
54	6	return _mro_to_chained(mro, dct.path)
55
56
57	6	def _retarget(ns_proxy):
58		"""Convert a class lookup to an instance lookup, if needed."""
59	6	dct, instance, owner = _PROXY_INFOS[ns_proxy]
60	6	if instance is None and isinstance(type(owner), _Namespaceable):
61	6	instance, owner = owner, type(owner)
62	6	dct = Namespace.get_namespace(owner, dct.path)
63	6	ns_proxy = _NamespaceProxy(dct, instance, owner)
64	6	return ns_proxy
65
66
67	6	class _NamespaceProxy(_Proxy):
68
69		"""Proxy object for manipulating and querying namespaces."""
70
71	6	__slots__ = '__weakref__',
72
73	6	def __init__(self, dct, instance, owner):
74	6	_PROXY_INFOS[self] = dct, instance, owner
75
76	6	def __dir__(self):
77	6	return collections.ChainMap(_instance_map(self), _mro_map(self))
78
79	6	def __getattribute__(self, name):
80	6	self = _retarget(self)
81	6	_, instance, owner = _PROXY_INFOS[self]
82	6	instance_map = _instance_map(self)
83	6	mro_map = _mro_map(self)
84	6	instance_value = ops.get(instance_map, name)
85	6	mro_value = ops.get(mro_map, name)
86	6	if ops.is_data(mro_value):
87	6	return mro_value.get(instance, owner)
88	6	elif issubclass(owner, type) and ops.has_get(instance_value):
89	6	return instance_value.get(None, instance)
90	6	elif instance_value is not None:
91	6	return instance_value.object
92	6	elif ops.has_get(mro_value):
93	6	return mro_value.get(instance, owner)
94	6	elif mro_value is not None:
95	6	return mro_value.object
96		else:
97	6	raise AttributeError(name)
98
99	6	def __setattr__(self, name, value):
100	6	self = _retarget(self)
101	6	dct, instance, owner = _PROXY_INFOS[self]
102	6	if instance is None:
103	6	real_map = Namespace.get_namespace(owner, dct.path)
104	6	real_map[name] = value
105	6	return
106	6	mro_map = _mro_map(self)
107	6	target_value = ops.get_data(mro_map, name)
108	6	if target_value is not None:
109		# These lines will be called on a data descriptor.
110	6	target_value.set(instance, value)
111	6	return
112	6	instance_map = Namespace.get_namespace(instance, dct.path)
113	6	instance_map[name] = value
114
115	6	def __delattr__(self, name):
116	6	self = _retarget(self)
117	6	dct, instance, owner = _PROXY_INFOS[self]
118	6	real_map = Namespace.get_namespace(owner, dct.path)
119	6	if instance is None:
120	6	ops.delete(real_map, name)
121	6	return
122	6	value = ops.get_data(real_map, name)
123	6	if value is not None:
124		# These lines will be called on a data descriptor.
125	6	value.delete(instance)
126	6	return
127	6	instance_map = Namespace.get_namespace(instance, dct.path)
128	6	ops.delete(instance_map, name)
129
130
131	6	_NAMESPACE_INFOS = weakref.WeakKeyDictionary()
132
133
134	6	class Namespace(dict):
135
136		"""Namespace."""
137
138	6	__slots__ = (
139		'name', 'scope', 'parent', 'active', 'parent_object', 'needs_setup')
140
141	6	__namespaces = {}
142
143	6	def __init__(self, args, *kwargs):
144	6	super().__init__(args, *kwargs)
145	6	bad_values = tuple(
146		value for value in self.values() if
147		isinstance(value, (Namespace, _Proxy)))
148	6	if bad_values:
149	6	raise ValueError('Bad values: {}'.format(bad_values))
150	6	self.name = None
151	6	self.scope = None
152	6	self.parent = None
153	6	self.active = False
154	6	self.parent_object = None
155	6	self.needs_setup = False
156
157	6	@classmethod
158		def premake(cls, name, parent):
159		"""Return an empty namespace with the given name and parent."""
160	6	self = cls()
161	6	self.name = name
162	6	self.parent = parent
163	6	return self
164
165		# Hold up. Do we need a symmetric addon to __delitem__?
166		# I forget how this works.
167	6	def __setitem__(self, key, value):
168	6	if (
169		self.scope is not None and
170		isinstance(value, self.scope.scope_proxy)):
171	6	value = self.scope.proxies[value]
172	6	if isinstance(value, (_ScopeProxy, _NamespaceProxy)):
173	6	raise ValueError('Cannot move scopes between classes.')
174	6	if isinstance(value, Namespace):
175	6	value.push(key, self.scope, self)
176	6	value.add(self.parent_object)
177	6	super().__setitem__(key, value)
178
179	6	def __enter__(self):
180	6	self.needs_setup = True
181	6	self.activate()
182	6	return self
183
184	6	def __exit__(self, exc_type, exc_value, traceback):
185	6	if self.name is None:
186	6	raise RuntimeError('Namespace must be named.')
187	6	self.deactivate()
188
189	6	@property
190		def path(self):
191		"""Return the full path of the namespace."""
192	6	if self.name is None or self.parent is None:
193		# This line can be hit by Namespace().path.
194	6	raise ValueError
195	6	if isinstance(self.parent, Namespace):
196	6	parent_path = self.parent.path
197		else:
198	6	parent_path = ()
199	6	return parent_path + (self.name,)
200
201	6	@classmethod
202		def __get_helper(cls, target, path):
203		"""Return the namespace for `target` at `path`, create if needed."""
204	6	if isinstance(target, _Namespaceable):
205	6	path_ = target, path
206	6	namespaces = cls.__namespaces
207		else:
208	6	path_ = path
209	6	try:
210	6	namespaces = _NAMESPACE_INFOS[target]
211	6	except KeyError:
212	6	namespaces = {}
213	6	_NAMESPACE_INFOS[target] = namespaces
214	6	return path_, namespaces
215
216	6	@classmethod
217		def namespace_exists(cls, path, target):
218		"""Return whether the given namespace exists."""
219	6	path_, namespaces = cls.__get_helper(target, path)
220	6	return path_ in namespaces
221
222	6	@classmethod
223		def get_namespace(cls, target, path):
224		"""Return a namespace with given target and path, create if needed."""
225	6	path_, namespaces = cls.__get_helper(target, path)
226	6	try:
227	6	return namespaces[path_]
228	6	except KeyError:
229	6	if len(path) == 1:
230	6	parent = {}
231		else:
232	6	parent = cls.get_namespace(target, path[:-1])
233	6	return namespaces.setdefault(path_, cls.premake(path[-1], parent))
234
235	6	@classmethod
236		def no_blocker(cls, path, cls_):
237		"""Return False if there's a non-Namespace object in the path."""
238	6	try:
239	6	namespace = vars(cls_)
240	6	for name in path:
241	6	namespace = namespace[name]
242	6	if not isinstance(namespace, cls):
243	6	return False
244	6	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...
245	6	pass
246	6	return True
247
248	6	def add(self, target):
249		"""Add self as a namespace under target."""
250	6	if target is not None:
251	6	path, namespaces = self.__get_helper(target, self.path)
252	6	res = namespaces.setdefault(path, self)
253	6	if res is self:
254	6	self.parent_object = target
255
256	6	def set_if_none(self, name, value):
257		"""Set the attribute `name` to `value`, if it's initially None."""
258	6	if getattr(self, name) is None:
259	6	setattr(self, name, value)
260
261	6	def validate_assignment(self, name, scope):
262		"""Confirm the instance can be assigned to the given name and scope."""
263	6	if name != self.name:
264	6	raise ValueError('Cannot rename namespace')
265	6	if scope is not self.scope:
266		# It should be possible to hit this line by assigning a namespace
267		# into another class. It may not be, however.
268	6	raise ValueError('Cannot reuse namespace')
269
270	6	def validate_parent(self, parent):
271		"""Confirm that the instance has the correct parent dict."""
272	6	if parent is not self.parent:
273		# This line can be hit by assigning a namespace into another
274		# namespace.
275	6	raise ValueError('Cannot reparent namespace')
276
277	6	def push(self, name, scope, parent):
278		"""Bind self to the given name and scope, and activate."""
279	6	self.set_if_none('name', name)
280	6	self.set_if_none('scope', scope)
281	6	self.set_if_none('parent', parent)
282	6	self.validate_assignment(name, scope)
283	6	self.validate_parent(parent)
284	6	self.scope.namespaces.append(self)
285	6	if self.needs_setup:
286	6	self.activate()
287
288	6	def activate(self):
289		"""Take over as the scope for the target."""
290	6	if self.active:
291	6	raise ValueError('Cannot double-activate.')
292	6	if self.scope is not None:
293	6	self.validate_parent(self.scope.head)
294	6	self.active = True
295	6	self.scope.push(self)
296	6	self.needs_setup = False
297
298	6	def deactivate(self):
299		"""Stop being the scope for the target."""
300	6	if self.scope is not None and self.active:
301	6	self.active = False
302	6	self.scope.pop_()
303
304	6	def total_length(self):
		0 ignored issues – show Coding Style introduced 2016-11-27 23:29 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...
305		return len(self) + sum(
306		ns.total_length() for ns in self.values() if
307		isinstance(ns, Namespace))
308
309	6	def __get__(self, instance, owner):
310	6	return _NamespaceProxy(self, instance, owner)
311
312	6	def __bool__(self):
		0 ignored issues – show Coding Style introduced 2016-11-26 17:09 UTC by Report Bug Copy Issue Report This method could be written as a function/class method. If a method does not access any attributes of the class, it could also be implemented as a function or static method. This can help improve readability. For example class Foo: def some_method(self, x, y): return x + y; could be written as class Foo: @classmethod def some_method(cls, x, y): return x + y; Loading history...
313	6	return True
314
315
316	6	class _NamespaceScope(collections.abc.MutableMapping):
317
318		"""The class creation namespace for _Namespaceables."""
319
320	6	__slots__ = '_dicts', 'namespaces', 'proxies', 'scope_proxy', 'finalized'
321
322	6	def __init__(self, dct):
323	6	self._dicts = [dct]
324	6	self.namespaces = []
325	6	self.proxies = proxies = weakref.WeakKeyDictionary()
326	6	self.finalized = False
327
328	6	class ScopeProxy(_ScopeProxy):
329
330		"""Local version of ScopeProxy for this scope."""
331
332	6	__slots__ = ()
333
334	6	def __init__(self, dct):
335	6	super().__init__(dct, proxies)
336
337	6	self.scope_proxy = ScopeProxy
338
339		# Mapping methods need to know about the dot syntax.
340		# Possibly namespaces themselves should know. Would simplify some things.
341
342	6	@property
343		def head(self):
344		"""The innermost Namespace scope."""
345	6	return self._dicts[0]
346
347	6	def finalize(self):
348		"""Mark the scope as no longer active, and return the head."""
349	6	if len(self._dicts) != 1:
350	6	raise ValueError('Cannot finalize a pushed scope!')
351	6	self.finalized = True
352	6	return self.head
353
354	6	def push(self, dct):
355		"""Add a new active Namespace to the scope."""
356	6	if self.finalized:
357	6	raise ValueError('Cannot push a finalized scope!')
358	6	self._dicts.insert(0, dct)
359
360	6	def pop_(self):
361		"""Remove the current active Namespace from the scope."""
362	6	if len(self._dicts) == 1:
363	6	raise ValueError('Cannot pop from a basal scope!')
364	6	self._dicts.pop(0)
365
366	6	def __getitem__(self, key):
367	6	value = collections.ChainMap(*self._dicts)[key]
368	6	if isinstance(value, Namespace):
369	6	value = self.scope_proxy(value)
370	6	return value
371
372	6	def _store(self, key, value, dct):
		0 ignored issues – show Coding Style introduced 2016-11-27 22:42 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...
373		# We just entered the context successfully.
374	6	if value is dct:
375	6	dct = self._dicts[1]
376	6	if isinstance(value, Namespace):
377	6	value.push(key, self, dct)
378	6	if isinstance(value, self.scope_proxy):
379	6	value = self.proxies[value]
380	6	value.validate_parent(dct)
381	6	value.validate_assignment(key, self)
382	6	return value, dct
383
384	6	def __setitem__(self, key, value):
385	6	dct = self.head
386	6	value, dct = self._store(key, value, dct)
387	6	if isinstance(value, (_ScopeProxy, _NamespaceProxy)):
388	6	raise ValueError('Cannot move scopes between classes.')
389	6	dct[key] = value
390
391	6	def __delitem__(self, key):
392	6	del self.head[key]
393
394		# These functions are incorrect and need to be rewritten.
395	6	def __iter__(self):
396	6	if not self.finalized:
397	6	raise ValueError('Iteration not defined on unfinalized scope.')
398
399	6	def __len__(self):
400	6	if not self.finalized:
401	6	raise ValueError('Length not defined on unfinalized scope.')
402	6	return len(self.head) + sum(
403		self.proxies[ns].total_length() for ns in self.head.values() if
404		isinstance(ns, self.scope_proxy))
405
406
407	6	_NAMESPACE_SCOPES = weakref.WeakKeyDictionary()
408
409
410	6	class _NamespaceBase:
411
412		"""Common base class for Namespaceable and its metaclass."""
413
414	6	__slots__ = ()
415
416		# Note: the dot format of invocation can "escape" self into other objects.
417		# This is not intended behavior, and the result of using dots "too deeply"
418		# should be considered undefined.
419		# I would like it to be an error, if I can figure out how.
420
421	6	@staticmethod
422		def __is_proxy(value):
		0 ignored issues – show Coding Style introduced 2016-11-25 16:00 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...
423	6	if not isinstance(value, _NamespaceProxy):
424		# This line can be hit by doing what the error message says.
425	6	raise ValueError('Given a dot attribute that went too deep.')
426	6	return value
427
428	6	def __getattribute__(self, name):
429	6	parent, is_namespace, name_ = name.rpartition('.')
430	6	if is_namespace:
431	6	self_ = self
432	6	for element in parent.split('.'):
433	6	self_ = self.__is_proxy(getattr(self_, element))
434	6	return getattr(getattr(self, parent), name_)
435	6	return super(_NamespaceBase, type(self)).__getattribute__(self, name)
436
437	6	def __setattr__(self, name, value):
438	6	parent, is_namespace, name_ = name.rpartition('.')
439	6	if is_namespace:
440	6	setattr(self.__is_proxy(getattr(self, parent)), name_, value)
441	6	return
442	6	super(_NamespaceBase, type(self)).__setattr__(self, name, value)
443
444	6	def __delattr__(self, name):
445	6	parent, is_namespace, name_ = name.rpartition('.')
446	6	if is_namespace:
447	6	delattr(self.__is_proxy(getattr(self, parent)), name_)
448	6	return
449		# This line can be hit by deleting an attribute that isn't a namespace.
450	6	super(_NamespaceBase, type(self)).__delattr__(self, name)
451
452
453	6	class _Namespaceable(_NamespaceBase, type):
454
455		"""Metaclass for classes that can contain namespaces.
456
457		Using the metaclass directly is a bad idea. Use a base class instead.
458		"""
459
460	6	@classmethod
461		def __prepare__(mcs, name, bases, **kwargs):
462	6	return _NamespaceScope(super().__prepare__(name, bases, **kwargs))
463
464	6	def __new__(mcs, name, bases, dct, **kwargs):
465	6	cls = super().__new__(mcs, name, bases, dct.finalize(), **kwargs)
466	6	if _DEFINED and not issubclass(cls, Namespaceable):
467		# This line can be hit with class(metaclass=type(Namespaceable)):
468	6	raise ValueError(
469		'Cannot create a _Namespaceable that does not inherit from '
470		'Namespaceable')
471	6	_NAMESPACE_SCOPES[cls] = dct
472	6	for namespace in dct.namespaces:
473	6	namespace.add(cls)
474	6	if ENABLE_SET_NAME:
475	2	for name, value in namespace.items():
476	2	wrapped = _DescriptorInspector(value)
477	2	if wrapped.has_set_name:
478	2	wrapped.set_name(cls, name)
479	6	return cls
480
481	6	def __setattr__(cls, name, value):
482	6	if (
483		'.' not in name and isinstance(value, Namespace) and
484		value.name != name):
485	6	scope = _NAMESPACE_SCOPES[cls]
486	6	value.push(name, scope, scope.head)
487	6	value.add(cls)
488	6	super(_Namespaceable, type(cls)).__setattr__(cls, name, value)
489
490
491	6	_DEFINED = False
492
493
494	6	class Namespaceable(_NamespaceBase, metaclass=_Namespaceable):
495
496		"""Base class for classes that can contain namespaces.
497
498		A note for people extending the functionality:
499		The base class for Namespaceable and its metaclass uses a non-standard
500		super() invocation in its definitions of several methods. This was the only
501		way I could find to mitigate some bugs I encountered with a standard
502		invocation. If you override any of methods defined on built-in types, I
503		recommend this form for maximal reusability:
504
505		super(class, type(self)).__method__(self, ...)
506
507		This avoids confusing error messages in case self is a subclass of class,
508		in addition to being an instance.
509
510		If you're not delegating above Namespaceable, you can probably use the
511		standard invocation, unless you bring about the above situation on your own
512		types.
513		"""
514
515
516		_DEFINED = True
517

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