We copied abc.py and test_abc.py from py3k svn and modified to work with 2.6.
After making all the changes we ran all the tests to ensure that no
other modules were affected.
Attached are abc.py, test_abc.py, and their relevant patches from 3.0 to 2.6.
On 8/25/07, Guido van Rossum <[EMAIL PROTECTED]> wrote:
> Um, that patch contains only the C code for overloading isinstance()
> and issubclass().
>
> Did you do anything about abc.py and _abcoll.py/collections.py and
> their respective unit tests? Or what about the unit tests for
> isinstance()/issubclass()?
>
> On 8/25/07, Benjamin Aranguren <[EMAIL PROTECTED]> wrote:
> > Worked with Alex Martelli at the Goolge Python Sprint.
>
> --
> --Guido van Rossum (home page: http://www.python.org/~guido/)
>
# Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""Abstract Base Classes (ABCs) according to PEP 3119."""
def abstractmethod(funcobj):
"""A decorator indicating abstract methods.
Requires that the metaclass is ABCMeta or derived from it. A
class that has a metaclass derived from ABCMeta cannot be
instantiated unless all of its abstract methods are overridden.
The abstract methods can be called using any of the the normal
'super' call mechanisms.
Usage:
class C(metaclass=ABCMeta):
@abstractmethod
def my_abstract_method(self, ...):
...
"""
funcobj.__isabstractmethod__ = True
return funcobj
class abstractproperty(property):
"""A decorator indicating abstract properties.
Requires that the metaclass is ABCMeta or derived from it. A
class that has a metaclass derived from ABCMeta cannot be
instantiated unless all of its abstract properties are overridden.
The abstract properties can be called using any of the the normal
'super' call mechanisms.
Usage:
class C(metaclass=ABCMeta):
@abstractproperty
def my_abstract_property(self):
...
This defines a read-only property; you can also define a read-write
abstract property using the 'long' form of property declaration:
class C(metaclass=ABCMeta):
def getx(self): ...
def setx(self, value): ...
x = abstractproperty(getx, setx)
"""
__isabstractmethod__ = True
class _Abstract(object):
"""Helper class inserted into the bases by ABCMeta (using _fix_bases()).
You should never need to explicitly subclass this class.
There should never be a base class between _Abstract and object.
"""
def __new__(cls, *args, **kwds):
am = cls.__dict__.get("__abstractmethods__")
if am:
raise TypeError("Can't instantiate abstract class %s "
"with abstract methods %s" %
(cls.__name__, ", ".join(sorted(am))))
if (args or kwds) and cls.__init__ is object.__init__:
raise TypeError("Can't pass arguments to __new__ "
"without overriding __init__")
return object.__new__(cls)
@classmethod
def __subclasshook__(cls, subclass):
"""Abstract classes can override this to customize issubclass().
This is invoked early on by __subclasscheck__() below. It
should return True, False or NotImplemented. If it returns
NotImplemented, the normal algorithm is used. Otherwise, it
overrides the normal algorithm (and the outcome is cached).
"""
return NotImplemented
def _fix_bases(bases):
"""Helper method that inserts _Abstract in the bases if needed."""
for base in bases:
if issubclass(base, _Abstract):
# _Abstract is already a base (maybe indirectly)
return bases
if object in bases:
# Replace object with _Abstract
return tuple([_Abstract if base is object else base
for base in bases])
# Append _Abstract to the end
return bases + (_Abstract,)
class ABCMeta(type):
"""Metaclass for defining Abstract Base Classes (ABCs).
Use this metaclass to create an ABC. An ABC can be subclassed
directly, and then acts as a mix-in class. You can also register
unrelated concrete classes (even built-in classes) and unrelated
ABCs as 'virtual subclasses' -- these and their descendants will
be considered subclasses of the registering ABC by the built-in
issubclass() function, but the registering ABC won't show up in
their MRO (Method Resolution Order) nor will method
implementations defined by the registering ABC be callable (not
even via super()).
"""
# A global counter that is incremented each time a class is
# registered as a virtual subclass of anything. It forces the
# negative cache to be cleared before its next use.
_abc_invalidation_counter = 0
def __new__(mcls, name, bases, namespace):
bases = _fix_bases(bases)
cls = super(ABCMeta, mcls).__new__(mcls, name, bases, namespace)
# Compute set of abstract method names
abstracts = set(name
for name, value in namespace.items()
if getattr(value, "__isabstractmethod__", False))
for base in bases:
for name in getattr(base, "__abstractmethods__", set()):
value = getattr(cls, name, None)
if getattr(value, "__isabstractmethod__", False):
abstracts.add(name)
cls.__abstractmethods__ = abstracts
# Set up inheritance registry
cls._abc_registry = set()
cls._abc_cache = set()
cls._abc_negative_cache = set()
cls._abc_negative_cache_version = ABCMeta._abc_invalidation_counter
return cls
def register(cls, subclass):
"""Register a virtual subclass of an ABC."""
if not isinstance(cls, type):
raise TypeError("Can only register classes")
if issubclass(subclass, cls):
return # Already a subclass
# Subtle: test for cycles *after* testing for "already a subclass";
# this means we allow X.register(X) and interpret it as a no-op.
if issubclass(cls, subclass):
# This would create a cycle, which is bad for the algorithm below
raise RuntimeError("Refusing to create an inheritance cycle")
cls._abc_registry.add(subclass)
ABCMeta._abc_invalidation_counter += 1 # Invalidate negative cache
def _dump_registry(cls, file=None):
"""Debug helper to print the ABC registry."""
print >> file, "Class: %s.%s" % (cls.__module__, cls.__name__)
print >> file, "Inv.counter: %s" % ABCMeta._abc_invalidation_counter
for name in sorted(cls.__dict__.keys()):
if name.startswith("_abc_"):
value = getattr(cls, name)
print >> file, "%s: %r" % (name, value)
def __instancecheck__(cls, instance):
"""Override for isinstance(instance, cls)."""
return any(cls.__subclasscheck__(c)
for c in [instance.__class__, type(instance)])
def __subclasscheck__(cls, subclass):
"""Override for issubclass(subclass, cls)."""
# Check cache
if subclass in cls._abc_cache:
return True
# Check negative cache; may have to invalidate
if cls._abc_negative_cache_version < ABCMeta._abc_invalidation_counter:
# Invalidate the negative cache
cls._abc_negative_cache = set()
cls._abc_negative_cache_version = ABCMeta._abc_invalidation_counter
elif subclass in cls._abc_negative_cache:
return False
# Check the subclass hook
ok = cls.__subclasshook__(subclass)
if ok is not NotImplemented:
assert isinstance(ok, bool)
if ok:
cls._abc_cache.add(subclass)
else:
cls._abc_negative_cache.add(subclass)
return ok
# Check if it's a direct subclass
if cls in subclass.__mro__:
cls._abc_cache.add(subclass)
return True
# Check if it's a subclass of a registered class (recursive)
for rcls in cls._abc_registry:
if issubclass(subclass, rcls):
cls._abc_registry.add(subclass)
return True
# Check if it's a subclass of a subclass (recursive)
for scls in cls.__subclasses__():
if issubclass(subclass, scls):
cls._abc_registry.add(subclass)
return True
# No dice; update negative cache
cls._abc_negative_cache.add(subclass)
return False
# Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""Unit tests for abc.py."""
import sys
import unittest
from test import test_support
import abc
__metaclass__ = type
class TestABC(unittest.TestCase):
def test_abstractmethod_basics(self):
@abc.abstractmethod
def foo(self): pass
self.assertEqual(foo.__isabstractmethod__, True)
def bar(self): pass
self.assertEqual(hasattr(bar, "__isabstractmethod__"), False)
def test_abstractproperty_basics(self):
@abc.abstractproperty
def foo(self): pass
self.assertEqual(foo.__isabstractmethod__, True)
def bar(self): pass
self.assertEqual(hasattr(bar, "__isabstractmethod__"), False)
class C:
__metaclass__ = abc.ABCMeta
@abc.abstractproperty
def foo(self): return 3
class D(C):
@property
def foo(self): return super(D, self).foo
self.assertEqual(D().foo, 3)
def test_abstractmethod_integration(self):
for abstractthing in [abc.abstractmethod, abc.abstractproperty]:
class C:
__metaclass__ = abc.ABCMeta
@abstractthing
def foo(self): pass # abstract
def bar(self): pass # concrete
self.assertEqual(C.__abstractmethods__, set(["foo"]))
self.assertRaises(TypeError, C) # because foo is abstract
class D(C):
def bar(self): pass # concrete override of concrete
self.assertEqual(D.__abstractmethods__, set(["foo"]))
self.assertRaises(TypeError, D) # because foo is still abstract
class E(D):
def foo(self): pass
self.assertEqual(E.__abstractmethods__, set())
E() # now foo is concrete, too
class F(E):
@abstractthing
def bar(self): pass # abstract override of concrete
self.assertEqual(F.__abstractmethods__, set(["bar"]))
self.assertRaises(TypeError, F) # because bar is abstract now
def test_registration_basics(self):
class A:
__metaclass__ = abc.ABCMeta
class B:
pass
b = B()
self.assertEqual(issubclass(B, A), False)
self.assertEqual(isinstance(b, A), False)
A.register(B)
self.assertEqual(issubclass(B, A), True)
self.assertEqual(isinstance(b, A), True)
class C(B):
pass
c = C()
self.assertEqual(issubclass(C, A), True)
self.assertEqual(isinstance(c, A), True)
def test_registration_builtins(self):
class A:
__metaclass__ = abc.ABCMeta
A.register(int)
self.assertEqual(isinstance(42, A), True)
self.assertEqual(issubclass(int, A), True)
class B(A):
pass
B.register(basestring)
self.assertEqual(isinstance("", A), True)
self.assertEqual(issubclass(str, A), True)
def test_registration_edge_cases(self):
class A:
__metaclass__ = abc.ABCMeta
A.register(A) # should pass silently
class A1(A):
pass
self.assertRaises(RuntimeError, A1.register, A) # cycles not allowed
class B:
pass
A1.register(B) # ok
A1.register(B) # should pass silently
class C(A):
pass
A.register(C) # should pass silently
self.assertRaises(RuntimeError, C.register, A) # cycles not allowed
C.register(B) # ok
def test_registration_transitiveness(self):
class A:
__metaclass__ = abc.ABCMeta
self.failUnless(issubclass(A, A))
class B:
__metaclass__ = abc.ABCMeta
self.failIf(issubclass(A, B))
self.failIf(issubclass(B, A))
class C:
__metaclass__ = abc.ABCMeta
A.register(B)
class B1(B):
pass
self.failUnless(issubclass(B1, A))
class C1(C):
pass
B1.register(C1)
self.failIf(issubclass(C, B))
self.failIf(issubclass(C, B1))
self.failUnless(issubclass(C1, A))
self.failUnless(issubclass(C1, B))
self.failUnless(issubclass(C1, B1))
C1.register(int)
class MyInt(int):
pass
self.failUnless(issubclass(MyInt, A))
self.failUnless(isinstance(42, A))
def test_main():
test_support.run_unittest(TestABC)
if __name__ == "__main__":
unittest.main()
--- abc.py 2007-08-22 23:17:54.000000000 -0700
+++ /opt/src/py26/Lib/abc.py 2007-08-25 10:35:37.000000000 -0700
@@ -120,11 +120,11 @@
def __new__(mcls, name, bases, namespace):
bases = _fix_bases(bases)
- cls = super().__new__(mcls, name, bases, namespace)
+ cls = super(ABCMeta, mcls).__new__(mcls, name, bases, namespace)
# Compute set of abstract method names
- abstracts = {name
+ abstracts = set(name
for name, value in namespace.items()
- if getattr(value, "__isabstractmethod__", False)}
+ if getattr(value, "__isabstractmethod__", False))
for base in bases:
for name in getattr(base, "__abstractmethods__", set()):
value = getattr(cls, name, None)
@@ -154,17 +154,17 @@
def _dump_registry(cls, file=None):
"""Debug helper to print the ABC registry."""
- print("Class: %s.%s" % (cls.__module__, cls.__name__), file=file)
- print("Inv.counter: %s" % ABCMeta._abc_invalidation_counter, file=file)
+ print >> file, "Class: %s.%s" % (cls.__module__, cls.__name__)
+ print >> file, "Inv.counter: %s" % ABCMeta._abc_invalidation_counter
for name in sorted(cls.__dict__.keys()):
if name.startswith("_abc_"):
value = getattr(cls, name)
- print("%s: %r" % (name, value), file=file)
+ print >> file, "%s: %r" % (name, value)
def __instancecheck__(cls, instance):
"""Override for isinstance(instance, cls)."""
return any(cls.__subclasscheck__(c)
- for c in {instance.__class__, type(instance)})
+ for c in [instance.__class__, type(instance)])
def __subclasscheck__(cls, subclass):
"""Override for issubclass(subclass, cls)."""
--- test_abc.py 2007-08-22 23:17:51.000000000 -0700
+++ /opt/src/py26/Lib/test/test_abc.py 2007-08-25 11:01:53.000000000 -0700
@@ -8,6 +8,7 @@
from test import test_support
import abc
+__metaclass__ = type
class TestABC(unittest.TestCase):
@@ -26,25 +27,27 @@
def bar(self): pass
self.assertEqual(hasattr(bar, "__isabstractmethod__"), False)
- class C(metaclass=abc.ABCMeta):
+ class C:
+ __metaclass__ = abc.ABCMeta
@abc.abstractproperty
def foo(self): return 3
class D(C):
@property
- def foo(self): return super().foo
+ def foo(self): return super(D, self).foo
self.assertEqual(D().foo, 3)
def test_abstractmethod_integration(self):
for abstractthing in [abc.abstractmethod, abc.abstractproperty]:
- class C(metaclass=abc.ABCMeta):
+ class C:
+ __metaclass__ = abc.ABCMeta
@abstractthing
def foo(self): pass # abstract
def bar(self): pass # concrete
- self.assertEqual(C.__abstractmethods__, {"foo"})
+ self.assertEqual(C.__abstractmethods__, set(["foo"]))
self.assertRaises(TypeError, C) # because foo is abstract
class D(C):
def bar(self): pass # concrete override of concrete
- self.assertEqual(D.__abstractmethods__, {"foo"})
+ self.assertEqual(D.__abstractmethods__, set(["foo"]))
self.assertRaises(TypeError, D) # because foo is still abstract
class E(D):
def foo(self): pass
@@ -53,12 +56,12 @@
class F(E):
@abstractthing
def bar(self): pass # abstract override of concrete
- self.assertEqual(F.__abstractmethods__, {"bar"})
+ self.assertEqual(F.__abstractmethods__, set(["bar"]))
self.assertRaises(TypeError, F) # because bar is abstract now
def test_registration_basics(self):
- class A(metaclass=abc.ABCMeta):
- pass
+ class A:
+ __metaclass__ = abc.ABCMeta
class B:
pass
b = B()
@@ -74,8 +77,8 @@
self.assertEqual(isinstance(c, A), True)
def test_registration_builtins(self):
- class A(metaclass=abc.ABCMeta):
- pass
+ class A:
+ __metaclass__ = abc.ABCMeta
A.register(int)
self.assertEqual(isinstance(42, A), True)
self.assertEqual(issubclass(int, A), True)
@@ -86,8 +89,8 @@
self.assertEqual(issubclass(str, A), True)
def test_registration_edge_cases(self):
- class A(metaclass=abc.ABCMeta):
- pass
+ class A:
+ __metaclass__ = abc.ABCMeta
A.register(A) # should pass silently
class A1(A):
pass
@@ -103,15 +106,15 @@
C.register(B) # ok
def test_registration_transitiveness(self):
- class A(metaclass=abc.ABCMeta):
- pass
+ class A:
+ __metaclass__ = abc.ABCMeta
self.failUnless(issubclass(A, A))
- class B(metaclass=abc.ABCMeta):
- pass
+ class B:
+ __metaclass__ = abc.ABCMeta
self.failIf(issubclass(A, B))
self.failIf(issubclass(B, A))
- class C(metaclass=abc.ABCMeta):
- pass
+ class C:
+ __metaclass__ = abc.ABCMeta
A.register(B)
class B1(B):
pass
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