Issue #23775: pprint() of OrderedDict now outputs the same representation

as repr().

Lib/pprint.py

@@ -34,10 +34,10 @@
 
 """
 
+import collections as _collections
 import re
 import sys as _sys
 import types as _types
-from collections import OrderedDict as _OrderedDict
 from io import StringIO as _StringIO
 
 __all__ = ["pprint","pformat","isreadable","isrecursive","saferepr",
@@ -188,16 +188,25 @@ def _pprint_dict(self, object, stream, indent, allowance, context, level):
             write((self._indent_per_level - 1) * ' ')
         length = len(object)
         if length:
-            if isinstance(object, _OrderedDict):
-                items = list(object.items())
-            else:
             items = sorted(object.items(), key=_safe_tuple)
             self._format_dict_items(items, stream, indent, allowance + 1,
                                     context, level)
         write('}')
 
     _dispatch[dict.__repr__] = _pprint_dict
-    _dispatch[_OrderedDict.__repr__] = _pprint_dict
+
+    def _pprint_ordered_dict(self, object, stream, indent, allowance, context, level):
+        if not len(object):
+            stream.write(repr(object))
+            return
+        cls = object.__class__
+        stream.write(cls.__name__ + '(')
+        self._format(list(object.items()), stream,
+                     indent + len(cls.__name__) + 1, allowance + 1,
+                     context, level)
+        stream.write(')')
+
+    _dispatch[_collections.OrderedDict.__repr__] = _pprint_ordered_dict
 
     def _pprint_list(self, object, stream, indent, allowance, context, level):
         stream.write('[')

Lib/test/test_pprint.py

@@ -272,19 +272,23 @@ def test_sorted_dict(self):
             r"{5: [[]], 'xy\tab\n': (3,), (): {}}")
 
     def test_ordered_dict(self):
+        d = collections.OrderedDict()
+        self.assertEqual(pprint.pformat(d, width=1), 'OrderedDict()')
+        d = collections.OrderedDict([])
+        self.assertEqual(pprint.pformat(d, width=1), 'OrderedDict()')
         words = 'the quick brown fox jumped over a lazy dog'.split()
         d = collections.OrderedDict(zip(words, itertools.count()))
         self.assertEqual(pprint.pformat(d),
 """\
-{'the': 0,
+OrderedDict([('the', 0),
- 'quick': 1,
+             ('quick', 1),
- 'brown': 2,
+             ('brown', 2),
- 'fox': 3,
+             ('fox', 3),
- 'jumped': 4,
+             ('jumped', 4),
- 'over': 5,
+             ('over', 5),
- 'a': 6,
+             ('a', 6),
- 'lazy': 7,
+             ('lazy', 7),
- 'dog': 8}""")
+             ('dog', 8)])""")
 
     def test_mapping_proxy(self):
         words = 'the quick brown fox jumped over a lazy dog'.split()
@@ -303,15 +307,15 @@ def test_mapping_proxy(self):
         d = collections.OrderedDict(zip(words, itertools.count()))
         m = types.MappingProxyType(d)
         self.assertEqual(pprint.pformat(m), """\
-mappingproxy({'the': 0,
+mappingproxy(OrderedDict([('the', 0),
-              'quick': 1,
+                          ('quick', 1),
-              'brown': 2,
+                          ('brown', 2),
-              'fox': 3,
+                          ('fox', 3),
-              'jumped': 4,
+                          ('jumped', 4),
-              'over': 5,
+                          ('over', 5),
-              'a': 6,
+                          ('a', 6),
-              'lazy': 7,
+                          ('lazy', 7),
-              'dog': 8})""")
+                          ('dog', 8)]))""")
 
     def test_subclassing(self):
         o = {'names with spaces': 'should be presented using repr()',

Misc/NEWS

@@ -30,6 +30,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #23775: pprint() of OrderedDict now outputs the same representation
+  as repr().
+
 - Issue #23765: Removed IsBadStringPtr calls in ctypes
 
 - Issue #22364: Improved some re error messages using regex for hints.