Issue #6081: Add str.format_map. str.format_map(mapping) is similar to str.format(**mapping), except mapping does not get converted to a dict.
diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 7927834..cc891bd 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -695,6 +695,84 @@
self.assertRaises(ValueError, format, '', '#')
self.assertRaises(ValueError, format, '', '#20')
+ def test_format_map(self):
+ self.assertEqual(''.format_map({}), '')
+ self.assertEqual('a'.format_map({}), 'a')
+ self.assertEqual('ab'.format_map({}), 'ab')
+ self.assertEqual('a{{'.format_map({}), 'a{')
+ self.assertEqual('a}}'.format_map({}), 'a}')
+ self.assertEqual('{{b'.format_map({}), '{b')
+ self.assertEqual('}}b'.format_map({}), '}b')
+ self.assertEqual('a{{b'.format_map({}), 'a{b')
+
+ # using mappings
+ class Mapping(dict):
+ def __missing__(self, key):
+ return key
+ self.assertEqual('{hello}'.format_map(Mapping()), 'hello')
+ self.assertEqual('{a} {world}'.format_map(Mapping(a='hello')), 'hello world')
+
+ class InternalMapping:
+ def __init__(self):
+ self.mapping = {'a': 'hello'}
+ def __getitem__(self, key):
+ return self.mapping[key]
+ self.assertEqual('{a}'.format_map(InternalMapping()), 'hello')
+
+
+ # classes we'll use for testing
+ class C:
+ def __init__(self, x=100):
+ self._x = x
+ def __format__(self, spec):
+ return spec
+
+ class D:
+ def __init__(self, x):
+ self.x = x
+ def __format__(self, spec):
+ return str(self.x)
+
+ # class with __str__, but no __format__
+ class E:
+ def __init__(self, x):
+ self.x = x
+ def __str__(self):
+ return 'E(' + self.x + ')'
+
+ # class with __repr__, but no __format__ or __str__
+ class F:
+ def __init__(self, x):
+ self.x = x
+ def __repr__(self):
+ return 'F(' + self.x + ')'
+
+ # class with __format__ that forwards to string, for some format_spec's
+ class G:
+ def __init__(self, x):
+ self.x = x
+ def __str__(self):
+ return "string is " + self.x
+ def __format__(self, format_spec):
+ if format_spec == 'd':
+ return 'G(' + self.x + ')'
+ return object.__format__(self, format_spec)
+
+ # class that returns a bad type from __format__
+ class H:
+ def __format__(self, format_spec):
+ return 1.0
+
+ self.assertEqual('{foo._x}'.format_map({'foo': C(20)}), '20')
+
+ # test various errors
+ self.assertRaises(TypeError, '{'.format_map)
+ self.assertRaises(TypeError, '}'.format_map)
+ self.assertRaises(TypeError, 'a{'.format_map)
+ self.assertRaises(TypeError, 'a}'.format_map)
+ self.assertRaises(TypeError, '{a'.format_map)
+ self.assertRaises(TypeError, '}a'.format_map)
+
def test_format_auto_numbering(self):
class C:
def __init__(self, x=100):