zope.security.checker

Security Checkers

You can set the environment variable ZOPE_WATCH_CHECKERS to get additional security checker debugging output on the standard error.

Setting ZOPE_WATCH_CHECKERS to 1 will display messages about unauthorized or forbidden attribute access. Setting it to a larger number will also display messages about granted attribute access.

Note that the ZOPE_WATCH_CHECKERS mechanism will eventually be replaced with a more general security auditing mechanism.

zope.security.checker.ProxyFactory(object, checker=None)[source]

Factory function that creates a proxy for an object

The proxy checker is looked up if not provided.

zope.security.checker.canWrite(obj, name)[source]

Check whether the interaction may write an attribute named name on obj.

Convenience method. Rather than using checkPermission in high level code, use canWrite and canAccess to avoid binding code to permissions.

zope.security.checker.canAccess(obj, name)[source]

Check whether the interaction may access an attribute named name on obj.

Convenience method. Rather than using checkPermission in high level code, use canWrite and canAccess to avoid binding code to permissions.

class zope.security.checker.Global(name, module=None)[source]

Bases: object

A global object that behaves like a string.

We want this to behave as a global, meaning it’s pickled by name, rather than value. We need to arrange that it has a suitable __reduce__.

zope.security.checker.NamesChecker(names=(), permission_id=Global(CheckerPublic, zope.security.checker), **__kw__)[source]

Return a checker that grants access to a set of names.

A sequence of names is given as the first argument. If a second argument, permission_id, is given, it is the permission required to access the names. Additional names and permission ids can be supplied as keyword arguments.

zope.security.checker.MultiChecker(specs)[source]

Create a checker from a sequence of specifications

A specification is:

  • A two-tuple with:

    o a sequence of names or an interface

    o a permission id

    All the names in the sequence of names or the interface are protected by the permission.

  • A dictionoid (having an items method), with items that are name/permission-id pairs.

zope.security.checker.selectCheckerPy(object)[source]

Get a checker for the given object

The appropriate checker is returned or None is returned. If the return value is None, then object should not be wrapped in a proxy.

zope.security.checker.defineChecker(type_, checker)[source]

Define a checker for a given type of object

The checker can be a Checker, or a function that, when called with an object, returns a Checker.

class zope.security.checker.CheckerLoggingMixin[source]

Bases: object

Debugging mixin for checkers.

Prints verbose debugging information about every performed check to sys.stderr.

If verbosity is set to 1, only displays Unauthorized and Forbidden messages. If verbosity is set to a larger number, displays all messages.

class zope.security.checker.Checker[source]

Bases: object

Security checker

check()

check(object, opname) – Check whether an operation is allowes

check_getattr()

check_getattr(object, name) – Check whether a getattr is allowes

check_setattr()

check_setattr(object, name) – Check whether a setattr is allowes

get_permissions

getattr name to permission dictionary

permission_id()

permission_id(name) – Return the permission neded to get the name

proxy()

proxy(object) – Security-proxy an object

set_permissions

setattr name to permission dictionary

setattr_permission_id()

setattr_permission_id(name) – Return the permission neded to set the name

class zope.security.checker.CombinedChecker(checker1, checker2)[source]

Bases: zope.security.checker.Checker

A checker that combines two other checkers in a logical-or fashion.

The following table describes the result of a combined checker in detail.

checker1 checker2 CombinedChecker(checker1, checker2) —————— —————— ———————————– ok anything ok (checker2 is never called) Unauthorized ok ok Unauthorized Unauthorized Unauthorized Unauthorized ForbiddenAttribute Unauthorized ForbiddenAttribute ok ok ForbiddenAttribute Unauthorized Unauthorized ForbiddenAttribute ForbiddenAttribute ForbiddenAttribute —————— —————— ———————————–

check(object, name)[source]

See IChecker

check_getattr(object, name)

See IChecker

check_setattr(object, name)[source]

See IChecker

Protections for Modules

The zope.secuirty.checker.moduleChecker() API can be used to determine whether a module has been protected: Initially, there’s no checker defined for the module:

>>> from zope.security.checker import moduleChecker
>>> from zope.security.tests import test_zcml_functest
>>> moduleChecker(test_zcml_functest) is None
True

We can add a checker using zope.security.metaconfigure.protectModule():

>>> from zope.component import provideUtility
>>> from zope.security.metaconfigure import protectModule
>>> from zope.security.permission import Permission
>>> from zope.security.interfaces import IPermission
>>> TEST_PERM = 'zope.security.metaconfigure.test'
>>> perm = Permission(TEST_PERM, '')
>>> provideUtility(perm, IPermission, TEST_PERM)
>>> protectModule(test_zcml_functest, 'foo', TEST_PERM)

Now, the checker should exist and have an access dictionary with the name and permission:

>>> def pprint(ob, width=70):
...     from pprint import PrettyPrinter
...     PrettyPrinter(width=width).pprint(ob)
>>> checker = moduleChecker(test_zcml_functest)
>>> cdict = checker.get_permissions
>>> pprint(cdict)
{'foo': 'zope.security.metaconfigure.test'}

If we define additional names, they will be added to the dict:

>>> protectModule(test_zcml_functest, 'bar', TEST_PERM)
>>> protectModule(test_zcml_functest, 'baz', TEST_PERM)
>>> pprint(cdict)
{'bar': 'zope.security.metaconfigure.test',
 'baz': 'zope.security.metaconfigure.test',
 'foo': 'zope.security.metaconfigure.test'}

The allow directive creates actions for each named defined directly, or via interface:

>>> from zope.interface import Interface
>>> from zope.interface import Attribute
>>> from zope.security.metaconfigure import allow
>>> class I1(Interface):
...     def x(): pass
...     y = Attribute("Y")
>>> class I2(I1):
...     def a(): pass
...     b = Attribute("B")
>>> class AContext(object):
...     def __init__(self):
...         self.actions = []
...
...     def action(self, discriminator, callable, args):
...         self.actions.append(
...             {'discriminator': discriminator,
...              'callable': int(callable is protectModule),
...              'args': args})
...     module='testmodule'

>>> context = AContext()
>>> allow(context, attributes=['foo', 'bar'], interface=[I1, I2])
>>> context.actions.sort(key=lambda a: a['discriminator'])
>>> pprint(context.actions)
[{'args': ('testmodule', 'a', 'zope.Public'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'a')},
 {'args': ('testmodule', 'b', 'zope.Public'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'b')},
 {'args': ('testmodule', 'bar', 'zope.Public'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'bar')},
 {'args': ('testmodule', 'foo', 'zope.Public'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'foo')},
 {'args': ('testmodule', 'x', 'zope.Public'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'x')},
 {'args': ('testmodule', 'y', 'zope.Public'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'y')}]

The provide directive creates actions for each named defined directly, or via interface:

>>> from zope.security.metaconfigure import require
>>> class RContext(object):
...     def __init__(self):
...         self.actions = []
...     def action(self, discriminator, callable, args):
...         self.actions.append(
...             {'discriminator': discriminator,
...              'callable': int(callable is protectModule),
...              'args': args})
...     module='testmodule'

>>> context = RContext()
>>> require(context, attributes=['foo', 'bar'],
...         interface=[I1, I2], permission='p')

>>> context.actions.sort(key=lambda a: a['discriminator'])
>>> pprint(context.actions)
[{'args': ('testmodule', 'a', 'p'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'a')},
 {'args': ('testmodule', 'b', 'p'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'b')},
 {'args': ('testmodule', 'bar', 'p'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'bar')},
 {'args': ('testmodule', 'foo', 'p'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'foo')},
 {'args': ('testmodule', 'x', 'p'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'x')},
 {'args': ('testmodule', 'y', 'p'),
  'callable': 1,
  'discriminator': ('http://namespaces.zope.org/zope:module',
                    'testmodule',
                    'y')}]

Protections for standard objects

>>> from zope.security.checker import ProxyFactory
>>> from zope.security.interfaces import ForbiddenAttribute
>>> def check_forbidden_get(object, attr):
...     from zope.security.interfaces import ForbiddenAttribute
...     try:
...         return getattr(object, attr)
...     except ForbiddenAttribute as e:
...         return 'ForbiddenAttribute: %s' % e.args[0]
>>> def check_forbidden_setitem(object, item, value):
...     from zope.security.interfaces import ForbiddenAttribute
...     try:
...         object[item] = value
...     except ForbiddenAttribute as e:
...         return 'ForbiddenAttribute: %s' % e.args[0]
>>> def check_forbidden_delitem(object, item):
...     from zope.security.interfaces import ForbiddenAttribute
...     try:
...         del object[item]
...     except ForbiddenAttribute as e:
...         return 'ForbiddenAttribute: %s' % e.args[0]
>>> def check_forbidden_call(callable, *args): # **
...     from zope.security.interfaces import ForbiddenAttribute
...     try:
...         return callable(*args) # **
...     except ForbiddenAttribute as e:
...         return 'ForbiddenAttribute: %s' % e.args[0]

Rocks

Rocks are immuatle, non-callable objects without interesting methods. They don’t get proxied.

>>> int(type(ProxyFactory(  object()  )) is object)
1
>>> int(type(ProxyFactory(  1  )) is int)
1
>>> int(type(ProxyFactory(  1.0  )) is float)
1
>>> int(type(ProxyFactory(  1j  )) is complex)
1
>>> int(type(ProxyFactory(  None  )) is type(None))
1
>>> int(type(ProxyFactory(  'xxx'  )) is str)
1
>>> int(type(ProxyFactory(  True  )) is type(True))
1

Datetime-reltatd instances are rocks, too:

>>> from datetime import timedelta, datetime, date, time, tzinfo
>>> int(type(ProxyFactory(  timedelta(1)  )) is timedelta)
1
>>> int(type(ProxyFactory(  datetime(2000, 1, 1)  )) is datetime)
1
>>> int(type(ProxyFactory(  date(2000, 1, 1)  )) is date)
1
>>> int(type(ProxyFactory(  time()  )) is time)
1
>>> int(type(ProxyFactory(  tzinfo() )) is tzinfo)
1
>>> try:
...     from pytz import UTC
... except ImportError:  # pytz checker only if pytz is present.
...     1
... else:
...      int(type(ProxyFactory(  UTC )) is type(UTC))
1

dicts

We can do everything we expect to be able to do with proxied dicts.

>>> d = ProxyFactory({'a': 1, 'b': 2})
>>> check_forbidden_get(d, 'clear') # Verify that we are protected
'ForbiddenAttribute: clear'
>>> check_forbidden_setitem(d, 3, 4) # Verify that we are protected
'ForbiddenAttribute: __setitem__'
>>> d['a']
1
>>> len(d)
2
>>> sorted(list(d))
['a', 'b']
>>> d.get('a')
1
>>> int('a' in d)
1
>>> c = d.copy()
>>> check_forbidden_get(c, 'clear')
'ForbiddenAttribute: clear'
>>> int(str(c) in ("{'a': 1, 'b': 2}", "{'b': 2, 'a': 1}"))
1
>>> int(repr(c) in ("{'a': 1, 'b': 2}", "{'b': 2, 'a': 1}"))
1
>>> def sorted(x):
...    x = list(x)
...    x.sort()
...    return x
>>> sorted(d.keys())
['a', 'b']
>>> sorted(d.values())
[1, 2]
>>> sorted(d.items())
[('a', 1), ('b', 2)]

Always available (note, that dicts in python-3.x are not orderable, so we are not checking that under python > 2):

>>> int(d != d)
0
>>> int(bool(d))
1
>>> int(d.__class__ == dict)
1

lists

We can do everything we expect to be able to do with proxied lists.

>>> l = ProxyFactory([1, 2])
>>> check_forbidden_delitem(l, 0)
'ForbiddenAttribute: __delitem__'
>>> check_forbidden_setitem(l, 0, 3)
'ForbiddenAttribute: __setitem__'
>>> l[0]
1
>>> l[0:1]
[1]
>>> check_forbidden_setitem(l[:1], 0, 2)
'ForbiddenAttribute: __setitem__'
>>> len(l)
2
>>> tuple(l)
(1, 2)
>>> int(1 in l)
1
>>> l.index(2)
1
>>> l.count(2)
1
>>> str(l)
'[1, 2]'
>>> repr(l)
'[1, 2]'
>>> l + l
[1, 2, 1, 2]

Always available:

>>> int(l < l)
0
>>> int(l > l)
0
>>> int(l <= l)
1
>>> int(l >= l)
1
>>> int(l == l)
1
>>> int(l != l)
0
>>> int(bool(l))
1
>>> int(l.__class__ == list)
1

tuples

We can do everything we expect to be able to do with proxied tuples.

>>> from zope.security.checker import ProxyFactory
>>> l = ProxyFactory((1, 2))
>>> l[0]
1
>>> l[0:1]
(1,)
>>> len(l)
2
>>> list(l)
[1, 2]
>>> int(1 in l)
1
>>> str(l)
'(1, 2)'
>>> repr(l)
'(1, 2)'
>>> l + l
(1, 2, 1, 2)

Always available:

>>> int(l < l)
0
>>> int(l > l)
0
>>> int(l <= l)
1
>>> int(l >= l)
1
>>> int(l == l)
1
>>> int(l != l)
0
>>> int(bool(l))
1
>>> int(l.__class__ == tuple)
1

sets

we can do everything we expect to be able to do with proxied sets.

>>> us = set((1, 2))
>>> s = ProxyFactory(us)

>>> check_forbidden_get(s, 'add') # Verify that we are protected
'ForbiddenAttribute: add'
>>> check_forbidden_get(s, 'remove') # Verify that we are protected
'ForbiddenAttribute: remove'
>>> check_forbidden_get(s, 'discard') # Verify that we are protected
'ForbiddenAttribute: discard'
>>> check_forbidden_get(s, 'pop') # Verify that we are protected
'ForbiddenAttribute: pop'
>>> check_forbidden_get(s, 'clear') # Verify that we are protected
'ForbiddenAttribute: clear'

>>> len(s)
2

>>> 1 in s
True

>>> 1 not in s
False

>>> s.issubset(set((1,2,3)))
True

>>> s.issuperset(set((1,2,3)))
False

>>> c = s.union(set((2, 3)))
>>> sorted(c)
[1, 2, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s | set((2, 3))
>>> sorted(c)
[1, 2, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s | ProxyFactory(set((2, 3)))
>>> sorted(c)
[1, 2, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = set((2, 3)) | s
>>> sorted(c)
[1, 2, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s.intersection(set((2, 3)))
>>> sorted(c)
[2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s & set((2, 3))
>>> sorted(c)
[2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s & ProxyFactory(set((2, 3)))
>>> sorted(c)
[2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = set((2, 3)) & s
>>> sorted(c)
[2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s.difference(set((2, 3)))
>>> sorted(c)
[1]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s - ProxyFactory(set((2, 3)))
>>> sorted(c)
[1]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s - set((2, 3))
>>> sorted(c)
[1]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = set((2, 3)) - s
>>> sorted(c)
[3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s.symmetric_difference(set((2, 3)))
>>> sorted(c)
[1, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s ^ set((2, 3))
>>> sorted(c)
[1, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s ^ ProxyFactory(set((2, 3)))
>>> sorted(c)
[1, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = set((2, 3)) ^ s
>>> sorted(c)
[1, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s.copy()
>>> sorted(c)
[1, 2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> str(s) == str(us)
True

>>> repr(s) == repr(us)
True

Always available:

>>> s < us
False
>>> s > us
False
>>> s <= us
True
>>> s >= us
True
>>> s == us
True
>>> s != us
False

Note that you can’t compare proxied sets with other proxied sets due a limitaion in the set comparison functions which won’t work with any kind of proxy.

>>> bool(s)
True
>>> s.__class__ == set
True

frozensets

we can do everything we expect to be able to do with proxied frozensets.

>>> def check_forbidden_get(object, attr):
...     from zope.security.interfaces import ForbiddenAttribute
...     try:
...         return getattr(object, attr)
...     except ForbiddenAttribute as e:
...         return 'ForbiddenAttribute: %s' % e.args[0]
>>> from zope.security.checker import ProxyFactory
>>> from zope.security.interfaces import ForbiddenAttribute
>>> us = frozenset((1, 2))
>>> s = ProxyFactory(us)

>>> check_forbidden_get(s, 'add') # Verify that we are protected
'ForbiddenAttribute: add'
>>> check_forbidden_get(s, 'remove') # Verify that we are protected
'ForbiddenAttribute: remove'
>>> check_forbidden_get(s, 'discard') # Verify that we are protected
'ForbiddenAttribute: discard'
>>> check_forbidden_get(s, 'pop') # Verify that we are protected
'ForbiddenAttribute: pop'
>>> check_forbidden_get(s, 'clear') # Verify that we are protected
'ForbiddenAttribute: clear'

>>> len(s)
2

>>> 1 in s
True

>>> 1 not in s
False

>>> s.issubset(frozenset((1,2,3)))
True

>>> s.issuperset(frozenset((1,2,3)))
False

>>> c = s.union(frozenset((2, 3)))
>>> sorted(c)
[1, 2, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s | frozenset((2, 3))
>>> sorted(c)
[1, 2, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s | ProxyFactory(frozenset((2, 3)))
>>> sorted(c)
[1, 2, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = frozenset((2, 3)) | s
>>> sorted(c)
[1, 2, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s.intersection(frozenset((2, 3)))
>>> sorted(c)
[2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s & frozenset((2, 3))
>>> sorted(c)
[2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s & ProxyFactory(frozenset((2, 3)))
>>> sorted(c)
[2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = frozenset((2, 3)) & s
>>> sorted(c)
[2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s.difference(frozenset((2, 3)))
>>> sorted(c)
[1]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s - ProxyFactory(frozenset((2, 3)))
>>> sorted(c)
[1]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s - frozenset((2, 3))
>>> sorted(c)
[1]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = frozenset((2, 3)) - s
>>> sorted(c)
[3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s.symmetric_difference(frozenset((2, 3)))
>>> sorted(c)
[1, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s ^ frozenset((2, 3))
>>> sorted(c)
[1, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s ^ ProxyFactory(frozenset((2, 3)))
>>> sorted(c)
[1, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = frozenset((2, 3)) ^ s
>>> sorted(c)
[1, 3]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> c = s.copy()
>>> sorted(c)
[1, 2]
>>> check_forbidden_get(c, 'add')
'ForbiddenAttribute: add'

>>> str(s) == str(us)
True

>>> repr(s) == repr(us)
True

Always available:

>>> s < us
False
>>> s > us
False
>>> s <= us
True
>>> s >= us
True
>>> s == us
True
>>> s != us
False

Note that you can’t compare proxied sets with other proxied sets due a limitaion in the frozenset comparison functions which won’t work with any kind of proxy.

>>> bool(s)
True
>>> s.__class__ == frozenset
True

iterators

>>> [a for a in ProxyFactory(iter([1, 2]))]
[1, 2]
>>> list(ProxyFactory(iter([1, 2])))
[1, 2]
>>> list(ProxyFactory(iter((1, 2))))
[1, 2]
>>> list(ProxyFactory(iter({1:1, 2:2})))
[1, 2]
>>> def f():
...     for i in 1, 2:
...             yield i
...
>>> list(ProxyFactory(f()))
[1, 2]
>>> list(ProxyFactory(f)())
[1, 2]

We can iterate over custom sequences, too:

>>> class X(object):
...   d = 1, 2, 3
...   def __getitem__(self, i):
...      return self.d[i]
...
>>> x = X()

We can iterate over sequences

>>> list(x)
[1, 2, 3]

>>> from zope.security.checker import NamesChecker
>>> from zope.security.checker import ProxyFactory
>>> c = NamesChecker(['__getitem__', '__len__'])
>>> p = ProxyFactory(x, c)

Even if they are proxied

>>> list(p)
[1, 2, 3]

But if the class has an iter:

>>> X.__iter__ = lambda self: iter(self.d)
>>> list(x)
[1, 2, 3]

We shouldn’t be able to iterate if we don’t have an assertion:

>>> check_forbidden_call(list, p)
'ForbiddenAttribute: __iter__'

New-style classes

>>> from zope.security.checker import NamesChecker
>>> class C(object):
...    x = 1
...    y = 2
>>> C = ProxyFactory(C)
>>> check_forbidden_call(C)
'ForbiddenAttribute: __call__'
>>> check_forbidden_get(C, '__dict__')
'ForbiddenAttribute: __dict__'
>>> s = str(C)
>>> s = repr(C)
>>> int(C.__module__ == __name__)
1
>>> len(C.__bases__)
1
>>> len(C.__mro__)
2

Always available:

>>> int(C == C)
1
>>> int(C != C)
0
>>> int(bool(C))
1
>>> int(C.__class__ == type)
1

New-style Instances

>>> class C(object):
...    x = 1
...    y = 2
>>> c = ProxyFactory(C(), NamesChecker(['x']))
>>> check_forbidden_get(c, 'y')
'ForbiddenAttribute: y'
>>> check_forbidden_get(c, 'z')
'ForbiddenAttribute: z'
>>> c.x
1
>>> int(c.__class__ == C)
1

Always available:

>>> int(c == c)
1
>>> int(c != c)
0
>>> int(bool(c))
1
>>> int(c.__class__ == C)
1

Classic Classes

>>> class C:
...    x = 1
>>> C = ProxyFactory(C)
>>> check_forbidden_call(C)
'ForbiddenAttribute: __call__'
>>> check_forbidden_get(C, '__dict__')
'ForbiddenAttribute: __dict__'
>>> s = str(C)
>>> s = repr(C)
>>> int(C.__module__ == __name__)
1
>>> len(C.__bases__)
1

Always available:

>>> int(C == C)
1
>>> int(C != C)
0
>>> int(bool(C))
1

Classic Instances

>>> class C(object):
...    x, y = 1, 2
>>> c = ProxyFactory(C(), NamesChecker(['x']))
>>> check_forbidden_get(c, 'y')
'ForbiddenAttribute: y'
>>> check_forbidden_get(c, 'z')
'ForbiddenAttribute: z'
>>> c.x
1
>>> int(c.__class__ == C)
1

Always available:

>>> int(c == c)
1
>>> int(c != c)
0
>>> int(bool(c))
1
>>> int(c.__class__ == C)
1

Interfaces and declarations

We can still use interfaces though proxies:

>>> from zope.interface import directlyProvides
>>> from zope.interface import implementer
>>> from zope.interface import provider
>>> class I(Interface):
...     pass
>>> class IN(Interface):
...     pass
>>> class II(Interface):
...     pass
>>> @implementer(I)
... @provider(IN)
... class N(object):
...     pass
>>> n = N()
>>> directlyProvides(n, II)
>>> N = ProxyFactory(N)
>>> n = ProxyFactory(n)
>>> I.implementedBy(N)
True
>>> IN.providedBy(N)
True
>>> I.providedBy(n)
True
>>> II.providedBy(n)
True

abstract Base Classes

We work with the ABCMeta meta class:

>>> import abc
>>> class MyABC:
...     __metaclass__ = abc.ABCMeta
>>> class Foo(MyABC): pass
>>> class Bar(Foo): pass
>>> PBar = ProxyFactory(Bar)
>>> [c.__name__ for c in PBar.__mro__]
['Bar', 'Foo', 'MyABC', 'object']
>>> check_forbidden_call(PBar)
'ForbiddenAttribute: __call__'
>>> check_forbidden_get(PBar, '__dict__')
'ForbiddenAttribute: __dict__'
>>> s = str(PBar)
>>> s = repr(PBar)
>>> int(PBar.__module__ == __name__)
1
>>> len(PBar.__bases__)
1

Always available:

>>> int(PBar == PBar)
1
>>> int(PBar != PBar)
0
>>> int(bool(PBar))
1
>>> int(PBar.__class__ == type)
1