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pitroupitrou
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Issue #2534: speed up isinstance() and issubclass() by 50-70%, so as to
match Python 2.5 speed despite the __instancecheck__ / __subclasscheck__ mechanism. In the process, fix a bug where isinstance() and issubclass(), when given a tuple of classes as second argument, were looking up __instancecheck__ / __subclasscheck__ on the tuple rather than on each type object. Reviewed by Benjamin Peterson and Raymond Hettinger.
1 parent e2dffc0 commit ec569b7

8 files changed

Lines changed: 201 additions & 96 deletions

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‎Include/abstract.h‎

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Original file line numberDiff line numberDiff line change
@@ -1273,6 +1273,11 @@ PyAPI_FUNC(int) PyObject_IsSubclass(PyObject *object, PyObject *typeorclass);
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/* issubclass(object, typeorclass) */
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PyAPI_FUNC(int) _PyObject_RealIsInstance(PyObject *inst, PyObject *cls);
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PyAPI_FUNC(int) _PyObject_RealIsSubclass(PyObject *derived, PyObject *cls);
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#ifdef __cplusplus
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}
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#endif

‎Lib/test/test_abc.py‎

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@@ -75,15 +75,21 @@ class B(object):
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pass
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b = B()
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self.assertEqual(issubclass(B, A), False)
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self.assertEqual(issubclass(B, (A,)), False)
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self.assertEqual(isinstance(b, A), False)
80+
self.assertEqual(isinstance(b, (A,)), False)
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A.register(B)
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self.assertEqual(issubclass(B, A), True)
83+
self.assertEqual(issubclass(B, (A,)), True)
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self.assertEqual(isinstance(b, A), True)
85+
self.assertEqual(isinstance(b, (A,)), True)
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class C(B):
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pass
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c = C()
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self.assertEqual(issubclass(C, A), True)
90+
self.assertEqual(issubclass(C, (A,)), True)
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self.assertEqual(isinstance(c, A), True)
92+
self.assertEqual(isinstance(c, (A,)), True)
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def test_isinstance_invalidation(self):
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class A(metaclass=abc.ABCMeta):
@@ -92,22 +98,29 @@ class B:
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pass
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b = B()
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self.assertEqual(isinstance(b, A), False)
101+
self.assertEqual(isinstance(b, (A,)), False)
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A.register(B)
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self.assertEqual(isinstance(b, A), True)
104+
self.assertEqual(isinstance(b, (A,)), True)
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def test_registration_builtins(self):
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class A(metaclass=abc.ABCMeta):
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pass
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A.register(int)
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self.assertEqual(isinstance(42, A), True)
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self.assertEqual(isinstance(42, (A,)), True)
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self.assertEqual(issubclass(int, A), True)
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self.assertEqual(issubclass(int, (A,)), True)
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class B(A):
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pass
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B.register(str)
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class C(str): pass
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self.assertEqual(isinstance("", A), True)
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self.assertEqual(isinstance("", (A,)), True)
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self.assertEqual(issubclass(str, A), True)
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self.assertEqual(issubclass(str, (A,)), True)
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self.assertEqual(issubclass(C, A), True)
123+
self.assertEqual(issubclass(C, (A,)), True)
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112125
def test_registration_edge_cases(self):
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class A(metaclass=abc.ABCMeta):
@@ -130,29 +143,40 @@ def test_registration_transitiveness(self):
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class A(metaclass=abc.ABCMeta):
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pass
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self.failUnless(issubclass(A, A))
146+
self.failUnless(issubclass(A, (A,)))
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class B(metaclass=abc.ABCMeta):
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pass
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self.failIf(issubclass(A, B))
150+
self.failIf(issubclass(A, (B,)))
136151
self.failIf(issubclass(B, A))
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self.failIf(issubclass(B, (A,)))
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class C(metaclass=abc.ABCMeta):
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pass
139155
A.register(B)
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class B1(B):
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pass
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self.failUnless(issubclass(B1, A))
159+
self.failUnless(issubclass(B1, (A,)))
143160
class C1(C):
144161
pass
145162
B1.register(C1)
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self.failIf(issubclass(C, B))
164+
self.failIf(issubclass(C, (B,)))
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self.failIf(issubclass(C, B1))
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self.failIf(issubclass(C, (B1,)))
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self.failUnless(issubclass(C1, A))
168+
self.failUnless(issubclass(C1, (A,)))
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self.failUnless(issubclass(C1, B))
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self.failUnless(issubclass(C1, (B,)))
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self.failUnless(issubclass(C1, B1))
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self.failUnless(issubclass(C1, (B1,)))
151173
C1.register(int)
152174
class MyInt(int):
153175
pass
154176
self.failUnless(issubclass(MyInt, A))
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self.failUnless(issubclass(MyInt, (A,)))
155178
self.failUnless(isinstance(42, A))
179+
self.failUnless(isinstance(42, (A,)))
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157181
def test_all_new_methods_are_called(self):
158182
class A(metaclass=abc.ABCMeta):

‎Lib/test/test_exceptions.py‎

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Original file line numberDiff line numberDiff line change
@@ -582,12 +582,18 @@ class MyException(Exception, metaclass=Meta):
582582
except KeyError:
583583
pass
584584
except:
585-
self.fail("Should have raised TypeError")
585+
self.fail("Should have raised KeyError")
586586
else:
587-
self.fail("Should have raised TypeError")
588-
self.assertEqual(stderr.getvalue(),
589-
"Exception ValueError: ValueError() "
590-
"in <class 'KeyError'> ignored\n")
587+
self.fail("Should have raised KeyError")
588+
589+
def g():
590+
try:
591+
return g()
592+
except RuntimeError:
593+
return sys.exc_info()
594+
e, v, tb = g()
595+
self.assert_(isinstance(v, RuntimeError), type(v))
596+
self.assert_("maximum recursion depth exceeded" in str(v), str(v))
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592598

593599
def test_MemoryError(self):

‎Lib/test/test_typechecks.py‎

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Original file line numberDiff line numberDiff line change
@@ -33,26 +33,39 @@ def testIsSubclassInternal(self):
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def testIsSubclassBuiltin(self):
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self.assertEqual(issubclass(int, Integer), True)
36+
self.assertEqual(issubclass(int, (Integer,)), True)
3637
self.assertEqual(issubclass(float, Integer), False)
38+
self.assertEqual(issubclass(float, (Integer,)), False)
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3840
def testIsInstanceBuiltin(self):
3941
self.assertEqual(isinstance(42, Integer), True)
42+
self.assertEqual(isinstance(42, (Integer,)), True)
4043
self.assertEqual(isinstance(3.14, Integer), False)
44+
self.assertEqual(isinstance(3.14, (Integer,)), False)
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4246
def testIsInstanceActual(self):
4347
self.assertEqual(isinstance(Integer(), Integer), True)
48+
self.assertEqual(isinstance(Integer(), (Integer,)), True)
4449

4550
def testIsSubclassActual(self):
4651
self.assertEqual(issubclass(Integer, Integer), True)
52+
self.assertEqual(issubclass(Integer, (Integer,)), True)
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4854
def testSubclassBehavior(self):
4955
self.assertEqual(issubclass(SubInt, Integer), True)
56+
self.assertEqual(issubclass(SubInt, (Integer,)), True)
5057
self.assertEqual(issubclass(SubInt, SubInt), True)
58+
self.assertEqual(issubclass(SubInt, (SubInt,)), True)
5159
self.assertEqual(issubclass(Integer, SubInt), False)
60+
self.assertEqual(issubclass(Integer, (SubInt,)), False)
5261
self.assertEqual(issubclass(int, SubInt), False)
62+
self.assertEqual(issubclass(int, (SubInt,)), False)
5363
self.assertEqual(isinstance(SubInt(), Integer), True)
64+
self.assertEqual(isinstance(SubInt(), (Integer,)), True)
5465
self.assertEqual(isinstance(SubInt(), SubInt), True)
66+
self.assertEqual(isinstance(SubInt(), (SubInt,)), True)
5567
self.assertEqual(isinstance(42, SubInt), False)
68+
self.assertEqual(isinstance(42, (SubInt,)), False)
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5871
def test_main():

‎Misc/NEWS‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -12,6 +12,13 @@ What's New in Python 3.0 release candidate 1
1212
Core and Builtins
1313
-----------------
1414

15+
- Issue #2534: speed up isinstance() and issubclass() by 50-70%, so as to
16+
match Python 2.5 speed despite the __instancecheck__ / __subclasscheck__
17+
mechanism. In the process, fix a bug where isinstance() and issubclass(),
18+
when given a tuple of classes as second argument, were looking up
19+
__instancecheck__ / __subclasscheck__ on the tuple rather than on each
20+
type object.
21+
1522
- Issue #3663: Py_None was decref'd when printing SyntaxErrors.
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1724
- Issue #3657: Fix uninitialized memory read when pickling longs.

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