[py3] Added python_2_unicode_compatible decorator.

django/utils/encoding.py

@@ -39,6 +39,19 @@ def __str__(self):
         def __str__(self):
             return self.__unicode__().encode('utf-8')
 
+def python_2_unicode_compatible(klass):
+    """
+    A decorator that defines __unicode__ and __str__ methods under Python 2.
+    Under Python 3 it does nothing.
+
+    To support Python 2 and 3 with a single code base, define a __str__ method
+    returning text and apply this decorator to the class.
+    """
+    if not six.PY3:
+        klass.__unicode__ = klass.__str__
+        klass.__str__ = lambda self: self.__unicode__().encode('utf-8')
+    return klass
+
 def smart_text(s, encoding='utf-8', strings_only=False, errors='strict'):
     """
     Returns a text object representing 's' -- unicode on Python 2 and str on

docs/ref/utils.txt

@@ -187,6 +187,14 @@ The functions defined in this module share the following properties:
     Useful as a mix-in. If you support Python 2 and 3 with a single code base,
     you can inherit this mix-in and just define ``__unicode__``.
 
+.. function:: python_2_unicode_compatible
+
+    A decorator that defines ``__unicode__`` and ``__str__`` methods under
+    Python 2. Under Python 3 it does nothing.
+
+    To support Python 2 and 3 with a single code base, define a ``__str__``
+    method returning text and apply this decorator to the class.
+
 .. function:: smart_text(s, encoding='utf-8', strings_only=False, errors='strict')
 
     .. versionadded:: 1.5