Issue 7994: Make object.__format__() raise a PendingDeprecationWarning
if the format string is not empty. Manually merge r79596 and r84772 from 2.x. Also, apparently test_format() from test_builtin never made it into 3.x. I've added it as well. It tests the basic format() infrastructure.
This commit is contained in:
Eric Smith
parent
af9d10aa30
commit
e4d6317c87
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@ -1279,6 +1279,116 @@ class BuiltinTest(unittest.TestCase):
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return i
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self.assertRaises(ValueError, list, zip(BadSeq(), BadSeq()))
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def test_format(self):
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# Test the basic machinery of the format() builtin. Don't test
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# the specifics of the various formatters
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self.assertEqual(format(3, ''), '3')
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# Returns some classes to use for various tests. There's
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# an old-style version, and a new-style version
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def classes_new():
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class A(object):
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def __init__(self, x):
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self.x = x
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def __format__(self, format_spec):
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return str(self.x) + format_spec
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class DerivedFromA(A):
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pass
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class Simple(object): pass
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class DerivedFromSimple(Simple):
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def __init__(self, x):
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self.x = x
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def __format__(self, format_spec):
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return str(self.x) + format_spec
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class DerivedFromSimple2(DerivedFromSimple): pass
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return A, DerivedFromA, DerivedFromSimple, DerivedFromSimple2
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def class_test(A, DerivedFromA, DerivedFromSimple, DerivedFromSimple2):
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self.assertEqual(format(A(3), 'spec'), '3spec')
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self.assertEqual(format(DerivedFromA(4), 'spec'), '4spec')
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self.assertEqual(format(DerivedFromSimple(5), 'abc'), '5abc')
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self.assertEqual(format(DerivedFromSimple2(10), 'abcdef'),
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'10abcdef')
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class_test(*classes_new())
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def empty_format_spec(value):
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# test that:
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# format(x, '') == str(x)
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# format(x) == str(x)
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self.assertEqual(format(value, ""), str(value))
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self.assertEqual(format(value), str(value))
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# for builtin types, format(x, "") == str(x)
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empty_format_spec(17**13)
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empty_format_spec(1.0)
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empty_format_spec(3.1415e104)
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empty_format_spec(-3.1415e104)
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empty_format_spec(3.1415e-104)
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empty_format_spec(-3.1415e-104)
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empty_format_spec(object)
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empty_format_spec(None)
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# TypeError because self.__format__ returns the wrong type
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class BadFormatResult:
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def __format__(self, format_spec):
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return 1.0
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self.assertRaises(TypeError, format, BadFormatResult(), "")
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# TypeError because format_spec is not unicode or str
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self.assertRaises(TypeError, format, object(), 4)
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self.assertRaises(TypeError, format, object(), object())
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# tests for object.__format__ really belong elsewhere, but
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# there's no good place to put them
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x = object().__format__('')
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self.assertTrue(x.startswith('<object object at'))
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# first argument to object.__format__ must be string
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self.assertRaises(TypeError, object().__format__, 3)
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self.assertRaises(TypeError, object().__format__, object())
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self.assertRaises(TypeError, object().__format__, None)
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# --------------------------------------------------------------------
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# Issue #7994: object.__format__ with a non-empty format string is
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# pending deprecated
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def test_deprecated_format_string(obj, fmt_str, should_raise_warning):
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with warnings.catch_warnings(record=True) as w:
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warnings.simplefilter("always", PendingDeprecationWarning)
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format(obj, fmt_str)
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if should_raise_warning:
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self.assertEqual(len(w), 1)
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self.assertIsInstance(w[0].message, PendingDeprecationWarning)
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self.assertIn('object.__format__ with a non-empty format '
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'string', str(w[0].message))
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else:
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self.assertEqual(len(w), 0)
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fmt_strs = ['', 's']
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class A:
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def __format__(self, fmt_str):
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return format('', fmt_str)
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for fmt_str in fmt_strs:
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test_deprecated_format_string(A(), fmt_str, False)
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class B:
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pass
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class C(object):
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pass
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for cls in [object, B, C]:
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for fmt_str in fmt_strs:
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test_deprecated_format_string(cls(), fmt_str, len(fmt_str) != 0)
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# --------------------------------------------------------------------
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# make sure we can take a subclass of str as a format spec
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class DerivedFromStr(str): pass
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self.assertEqual(format(0, DerivedFromStr('10')), ' 0')
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def test_bin(self):
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self.assertEqual(bin(0), '0b0')
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self.assertEqual(bin(1), '0b1')
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@ -609,12 +609,15 @@ class UnicodeTest(string_tests.CommonTest,
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self.assertEqual('{0}'.format({}), '{}')
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self.assertEqual('{0}'.format([]), '[]')
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self.assertEqual('{0}'.format([1]), '[1]')
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self.assertEqual('{0}'.format(E('data')), 'E(data)')
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self.assertEqual('{0:d}'.format(G('data')), 'G(data)')
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self.assertEqual('{0!s}'.format(G('data')), 'string is data')
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msg = 'object.__format__ with a non-empty format string is deprecated'
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with support.check_warnings((msg, PendingDeprecationWarning)):
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self.assertEqual('{0:^10}'.format(E('data')), ' E(data) ')
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self.assertEqual('{0:^10s}'.format(E('data')), ' E(data) ')
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self.assertEqual('{0:d}'.format(G('data')), 'G(data)')
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self.assertEqual('{0:>15s}'.format(G('data')), ' string is data')
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self.assertEqual('{0!s}'.format(G('data')), 'string is data')
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self.assertEqual("{0:date: %Y-%m-%d}".format(I(year=2007,
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month=8,
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@ -10,6 +10,14 @@ What's New in Python 3.2 Alpha 3?
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Core and Builtins
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-----------------
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- Issue #7994: Issue a PendingDeprecationWarning if object.__format__
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is called with a non-empty format string. This is an effort to
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future-proof user code. If a derived class does not currently
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implement __format__ but later adds its own __format__, it would
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most likely break user code that had supplied a format string. This
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will be changed to a DeprecationWaring in Python 3.3 and it will be
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an error in Python 3.4.
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- Issue #9828: Destroy the GIL in Py_Finalize(), so that it gets properly
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re-created on a subsequent call to Py_Initialize(). The problem (a crash)
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wouldn't appear in 3.1 or 2.7 where the GIL's structure is more trivial.
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@ -3315,9 +3315,26 @@ object_format(PyObject *self, PyObject *args)
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return NULL;
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self_as_str = PyObject_Str(self);
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if (self_as_str != NULL)
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result = PyObject_Format(self_as_str, format_spec);
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if (self_as_str != NULL) {
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/* Issue 7994: If we're converting to a string, we
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should reject format specifications */
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if (PyUnicode_GET_SIZE(format_spec) > 0) {
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if (PyErr_WarnEx(PyExc_PendingDeprecationWarning,
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"object.__format__ with a non-empty format "
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"string is deprecated", 1) < 0) {
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goto done;
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}
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/* Eventually this will become an error:
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PyErr_Format(PyExc_TypeError,
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"non-empty format string passed to object.__format__");
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goto done;
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*/
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}
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result = PyObject_Format(self_as_str, format_spec);
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}
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done:
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Py_XDECREF(self_as_str);
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return result;
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