Issue #14570: Document json sort_keys parameter properly.

Patch by Chris Rebert.

Doc/library/json.rst

@@ -117,7 +117,10 @@ Using json.tool from the shell to validate and pretty-print::
 Basic Usage
 -----------
 
-.. function:: dump(obj, fp[, skipkeys[, ensure_ascii[, check_circular[, allow_nan[, cls[, indent[, separators[, encoding[, default[, **kw]]]]]]]]]])
+.. function:: dump(obj, fp, skipkeys=False, ensure_ascii=True, \
+                   check_circular=True, allow_nan=True, cls=None, \
+                   indent=None, separators=None, encoding="utf-8", \
+                   default=None, sort_keys=False, **kw)
 
    Serialize *obj* as a JSON formatted stream to *fp* (a ``.write()``-supporting
    :term:`file-like object`).
@@ -159,6 +162,9 @@ Basic Usage
    *default(obj)* is a function that should return a serializable version of
    *obj* or raise :exc:`TypeError`.  The default simply raises :exc:`TypeError`.
 
+   If *sort_keys* is ``True`` (default: ``False``), then the output of
+   dictionaries will be sorted by key.
+
    To use a custom :class:`JSONEncoder` subclass (e.g. one that overrides the
    :meth:`default` method to serialize additional types), specify it with the
    *cls* kwarg; otherwise :class:`JSONEncoder` is used.
@@ -169,7 +175,10 @@ Basic Usage
       trying to serialize more objects with repeated calls to :func:`dump` and
       the same *fp* will result in an invalid JSON file.
 
-.. function:: dumps(obj[, skipkeys[, ensure_ascii[, check_circular[, allow_nan[, cls[, indent[, separators[, encoding[, default[, **kw]]]]]]]]]])
+.. function:: dumps(obj, skipkeys=False, ensure_ascii=True, \
+                    check_circular=True, allow_nan=True, cls=None, \
+                    indent=None, separators=None, encoding="utf-8", \
+                    default=None, sort_keys=False, **kw)
 
    Serialize *obj* to a JSON formatted :class:`str`.  If *ensure_ascii* is
    ``False``, the result may contain non-ASCII characters and the return value

Lib/json/__init__.py

@@ -121,7 +121,7 @@ _default_encoder = JSONEncoder(
 
 def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
         allow_nan=True, cls=None, indent=None, separators=None,
-        encoding='utf-8', default=None, **kw):
+        encoding='utf-8', default=None, sort_keys=False, **kw):
     """Serialize ``obj`` as a JSON formatted stream to ``fp`` (a
     ``.write()``-supporting file-like object).
 
@@ -161,6 +161,9 @@ def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
     ``default(obj)`` is a function that should return a serializable version
     of obj or raise TypeError. The default simply raises TypeError.
 
+    If *sort_keys* is ``True`` (default: ``False``), then the output of
+    dictionaries will be sorted by key.
+
     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
     ``.default()`` method to serialize additional types), specify it with
     the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.
@@ -170,7 +173,7 @@ def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
     if (not skipkeys and ensure_ascii and
         check_circular and allow_nan and
         cls is None and indent is None and separators is None and
-        encoding == 'utf-8' and default is None and not kw):
+        encoding == 'utf-8' and default is None and not sort_keys and not kw):
         iterable = _default_encoder.iterencode(obj)
     else:
         if cls is None:
@@ -178,7 +181,7 @@ def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
         iterable = cls(skipkeys=skipkeys, ensure_ascii=ensure_ascii,
             check_circular=check_circular, allow_nan=allow_nan, indent=indent,
             separators=separators, encoding=encoding,
-            default=default, **kw).iterencode(obj)
+            default=default, sort_keys=sort_keys, **kw).iterencode(obj)
     # could accelerate with writelines in some versions of Python, at
     # a debuggability cost
     for chunk in iterable:
@@ -187,7 +190,7 @@ def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
 
 def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
         allow_nan=True, cls=None, indent=None, separators=None,
-        encoding='utf-8', default=None, **kw):
+        encoding='utf-8', default=None, sort_keys=False, **kw):
     """Serialize ``obj`` to a JSON formatted ``str``.
 
     If ``skipkeys`` is false then ``dict`` keys that are not basic types
@@ -220,6 +223,9 @@ def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
     ``default(obj)`` is a function that should return a serializable version
     of obj or raise TypeError. The default simply raises TypeError.
 
+    If *sort_keys* is ``True`` (default: ``False``), then the output of
+    dictionaries will be sorted by key.
+
     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
     ``.default()`` method to serialize additional types), specify it with
     the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.
@@ -229,7 +235,7 @@ def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
     if (not skipkeys and ensure_ascii and
         check_circular and allow_nan and
         cls is None and indent is None and separators is None and
-        encoding == 'utf-8' and default is None and not kw):
+        encoding == 'utf-8' and default is None and not sort_keys and not kw):
         return _default_encoder.encode(obj)
     if cls is None:
         cls = JSONEncoder
@@ -237,7 +243,7 @@ def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
         skipkeys=skipkeys, ensure_ascii=ensure_ascii,
         check_circular=check_circular, allow_nan=allow_nan, indent=indent,
         separators=separators, encoding=encoding, default=default,
-        **kw).encode(obj)
+        sort_keys=sort_keys, **kw).encode(obj)
 
 
 _default_decoder = JSONDecoder(encoding=None, object_hook=None,