Introduced force_bytes and force_str.

This is consistent with the smart_* series of functions and it's going
to be used by the next commit.

django/utils/encoding.py

@@ -139,6 +139,19 @@ def smart_bytes(s, encoding='utf-8', strings_only=False, errors='strict'):
     """
     Returns a bytestring version of 's', encoded as specified in 'encoding'.
 
+    If strings_only is True, don't convert (some) non-string-like objects.
+    """
+    if isinstance(s, Promise):
+        # The input is the result of a gettext_lazy() call.
+        return s
+    return force_bytes(s, encoding, strings_only, errors)
+
+
+def force_bytes(s, encoding='utf-8', strings_only=False, errors='strict'):
+    """
+    Similar to smart_bytes, except that lazy instances are resolved to
+    strings, rather than kept as lazy objects.
+
     If strings_only is True, don't convert (some) non-string-like objects.
     """
     if isinstance(s, bytes):
@@ -169,8 +182,10 @@ def smart_bytes(s, encoding='utf-8', strings_only=False, errors='strict'):
 
 if six.PY3:
     smart_str = smart_text
+    force_str = force_text
 else:
     smart_str = smart_bytes
+    force_str = force_bytes
     # backwards compatibility for Python 2
     smart_unicode = smart_text
     force_unicode = force_text
@@ -181,6 +196,10 @@ Apply smart_text in Python 3 and smart_bytes in Python 2.
 This is suitable for writing to sys.stdout (for instance).
 """
 
+force_str.__doc__ = """\
+Apply force_text in Python 3 and force_bytes in Python 2.
+"""
+
 def iri_to_uri(iri):
     """
     Convert an Internationalized Resource Identifier (IRI) portion to a URI

docs/ref/utils.txt

@@ -240,14 +240,29 @@ The functions defined in this module share the following properties:
     If ``strings_only`` is ``True``, don't convert (some) non-string-like
     objects.
 
+.. function:: force_bytes(s, encoding='utf-8', strings_only=False, errors='strict')
+
+    .. versionadded:: 1.5
+
+    Similar to ``smart_bytes``, except that lazy instances are resolved to
+    bytestrings, rather than kept as lazy objects.
+
+    If ``strings_only`` is ``True``, don't convert (some) non-string-like
+    objects.
+
 .. function:: smart_str(s, encoding='utf-8', strings_only=False, errors='strict')
 
     Alias of :func:`smart_bytes` on Python 2 and :func:`smart_text` on Python
-    3. This function always returns a :class:`str`.
+    3. This function returns a :class:`str` or a lazy string.
 
     For instance, this is  suitable for writing to :attr:`sys.stdout` on
     Python 2 and 3.
 
+.. function:: force_str(s, encoding='utf-8', strings_only=False, errors='strict')
+
+    Alias of :func:`force_bytes` on Python 2 and :func:`force_text` on Python
+    3. This function always returns a :class:`str`.
+
 .. function:: iri_to_uri(iri)
 
     Convert an Internationalized Resource Identifier (IRI) portion to a URI