Backport of PEP 3101, Advanced String Formatting, from py3k.
Highlights:
- Adding PyObject_Format.
- Adding string.Format class.
- Adding __format__ for str, unicode, int, long, float, datetime.
- Adding builtin format.
- Adding ''.format and u''.format.
- str/unicode fixups for formatters.
The files in Objects/stringlib that implement PEP 3101 (stringdefs.h,
unicodedefs.h, formatter.h, string_format.h) are identical in trunk
and py3k. Any changes from here on should be made to trunk, and
changes will propogate to py3k).
diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index ddc5842..a5d1f92 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -2012,6 +2012,101 @@
data = 'The quick Brown fox Jumped over The lazy Dog'.split()
self.assertRaises(TypeError, sorted, data, None, lambda x,y: 0)
+ def test_format(self):
+ # Test the basic machinery of the format() builtin. Don't test
+ # the specifics of the various formatters
+ self.assertEqual(format(3, ''), '3')
+
+ # Returns some classes to use for various tests. There's
+ # an old-style version, and a new-style version
+ def classes_new():
+ class A(object):
+ def __init__(self, x):
+ self.x = x
+ def __format__(self, format_spec):
+ return str(self.x) + format_spec
+ class DerivedFromA(A):
+ pass
+
+ class Simple(object): pass
+ class DerivedFromSimple(Simple):
+ def __init__(self, x):
+ self.x = x
+ def __format__(self, format_spec):
+ return str(self.x) + format_spec
+ class DerivedFromSimple2(DerivedFromSimple): pass
+ return A, DerivedFromA, DerivedFromSimple, DerivedFromSimple2
+
+ # In 3.0, classes_classic has the same meaning as classes_new
+ def classes_classic():
+ class A:
+ def __init__(self, x):
+ self.x = x
+ def __format__(self, format_spec):
+ return str(self.x) + format_spec
+ class DerivedFromA(A):
+ pass
+
+ class Simple: pass
+ class DerivedFromSimple(Simple):
+ def __init__(self, x):
+ self.x = x
+ def __format__(self, format_spec):
+ return str(self.x) + format_spec
+ class DerivedFromSimple2(DerivedFromSimple): pass
+ return A, DerivedFromA, DerivedFromSimple, DerivedFromSimple2
+
+ def class_test(A, DerivedFromA, DerivedFromSimple, DerivedFromSimple2):
+ self.assertEqual(format(A(3), 'spec'), '3spec')
+ self.assertEqual(format(DerivedFromA(4), 'spec'), '4spec')
+ self.assertEqual(format(DerivedFromSimple(5), 'abc'), '5abc')
+ self.assertEqual(format(DerivedFromSimple2(10), 'abcdef'),
+ '10abcdef')
+
+ class_test(*classes_new())
+ class_test(*classes_classic())
+
+ def empty_format_spec(value):
+ # test that:
+ # format(x, '') == str(x)
+ # format(x) == str(x)
+ self.assertEqual(format(value, ""), str(value))
+ self.assertEqual(format(value), str(value))
+
+ # for builtin types, format(x, "") == str(x)
+ empty_format_spec(17**13)
+ empty_format_spec(1.0)
+ empty_format_spec(3.1415e104)
+ empty_format_spec(-3.1415e104)
+ empty_format_spec(3.1415e-104)
+ empty_format_spec(-3.1415e-104)
+ empty_format_spec(object)
+ empty_format_spec(None)
+
+ # TypeError because self.__format__ returns the wrong type
+ class BadFormatResult:
+ def __format__(self, format_spec):
+ return 1.0
+ self.assertRaises(TypeError, format, BadFormatResult(), "")
+
+ # TypeError because format_spec is not unicode or str
+ self.assertRaises(TypeError, format, object(), 4)
+ self.assertRaises(TypeError, format, object(), object())
+
+ # tests for object.__format__ really belong elsewhere, but
+ # there's no good place to put them
+ x = object().__format__('')
+ self.assert_(x.startswith('<object object at'))
+
+ # first argument to object.__format__ must be string
+ self.assertRaises(TypeError, object().__format__, 3)
+ self.assertRaises(TypeError, object().__format__, object())
+ self.assertRaises(TypeError, object().__format__, None)
+
+ # make sure we can take a subclass of str as a format spec
+ class DerivedFromStr(str): pass
+ self.assertEqual(format(0, DerivedFromStr('10')), ' 0')
+
def test_main(verbose=None):
test_classes = (BuiltinTest, TestSorted)