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).

1 files changed, 76 insertions, 0 deletions

diff --git a/Lib/test/test_datetime.py b/Lib/test/test_datetime.py
index 21b8890..cb639b4 100644
--- a/Lib/test/test_datetime.py
+++ b/Lib/test/test_datetime.py
@@ -854,6 +854,32 @@ class TestDate(HarmlessMixedComparison, unittest.TestCase):
         # A naive object replaces %z and %Z w/ empty strings.
         self.assertEqual(t.strftime("'%z' '%Z'"), "'' ''")
 
+    def test_format(self):
+        dt = self.theclass(2007, 9, 10)
+        self.assertEqual(dt.__format__(''), str(dt))
+
+        # check that a derived class's __str__() gets called
+        class A(self.theclass):
+            def __str__(self):
+                return 'A'
+        a = A(2007, 9, 10)
+        self.assertEqual(a.__format__(''), 'A')
+
+        # check that a derived class's strftime gets called
+        class B(self.theclass):
+            def strftime(self, format_spec):
+                return 'B'
+        b = B(2007, 9, 10)
+        self.assertEqual(b.__format__(''), str(dt))
+
+        for fmt in ["m:%m d:%d y:%y",
+                    "m:%m d:%d y:%y H:%H M:%M S:%S",
+                    "%z %Z",
+                    ]:
+            self.assertEqual(dt.__format__(fmt), dt.strftime(fmt))
+            self.assertEqual(a.__format__(fmt), dt.strftime(fmt))
+            self.assertEqual(b.__format__(fmt), 'B')
+
     def test_resolution_info(self):
         self.assert_(isinstance(self.theclass.min, self.theclass))
         self.assert_(isinstance(self.theclass.max, self.theclass))
@@ -1136,6 +1162,32 @@ class TestDateTime(TestDate):
         # str is ISO format with the separator forced to a blank.
         self.assertEqual(str(t), "0002-03-02 00:00:00")
 
+    def test_format(self):
+        dt = self.theclass(2007, 9, 10, 4, 5, 1, 123)
+        self.assertEqual(dt.__format__(''), str(dt))
+
+        # check that a derived class's __str__() gets called
+        class A(self.theclass):
+            def __str__(self):
+                return 'A'
+        a = A(2007, 9, 10, 4, 5, 1, 123)
+        self.assertEqual(a.__format__(''), 'A')
+
+        # check that a derived class's strftime gets called
+        class B(self.theclass):
+            def strftime(self, format_spec):
+                return 'B'
+        b = B(2007, 9, 10, 4, 5, 1, 123)
+        self.assertEqual(b.__format__(''), str(dt))
+
+        for fmt in ["m:%m d:%d y:%y",
+                    "m:%m d:%d y:%y H:%H M:%M S:%S",
+                    "%z %Z",
+                    ]:
+            self.assertEqual(dt.__format__(fmt), dt.strftime(fmt))
+            self.assertEqual(a.__format__(fmt), dt.strftime(fmt))
+            self.assertEqual(b.__format__(fmt), 'B')
+
     def test_more_ctime(self):
         # Test fields that TestDate doesn't touch.
         import time
@@ -1767,6 +1819,30 @@ class TestTime(HarmlessMixedComparison, unittest.TestCase):
         # A naive object replaces %z and %Z with empty strings.
         self.assertEqual(t.strftime("'%z' '%Z'"), "'' ''")
 
+    def test_format(self):
+        t = self.theclass(1, 2, 3, 4)
+        self.assertEqual(t.__format__(''), str(t))
+
+        # check that a derived class's __str__() gets called
+        class A(self.theclass):
+            def __str__(self):
+                return 'A'
+        a = A(1, 2, 3, 4)
+        self.assertEqual(a.__format__(''), 'A')
+
+        # check that a derived class's strftime gets called
+        class B(self.theclass):
+            def strftime(self, format_spec):
+                return 'B'
+        b = B(1, 2, 3, 4)
+        self.assertEqual(b.__format__(''), str(t))
+
+        for fmt in ['%H %M %S',
+                    ]:
+            self.assertEqual(t.__format__(fmt), t.strftime(fmt))
+            self.assertEqual(a.__format__(fmt), t.strftime(fmt))
+            self.assertEqual(b.__format__(fmt), 'B')
+
     def test_str(self):
         self.assertEqual(str(self.theclass(1, 2, 3, 4)), "01:02:03.000004")
         self.assertEqual(str(self.theclass(10, 2, 3, 4000)), "10:02:03.004000")