#4785: document strict argument of JSONDecoder, plus add object_pairs_hook in the docstrings.

Doc/library/json.rst

@@ -149,7 +149,7 @@ Basic Usage
 
    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.
+   *cls* kwarg; otherwise :class:`JSONEncoder` is used.
 
 
 .. function:: dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True, allow_nan=True, cls=None, indent=None, separators=None, default=None, **kw)
@@ -195,8 +195,8 @@ Basic Usage
    are encountered.
 
    To use a custom :class:`JSONDecoder` subclass, specify it with the ``cls``
-   kwarg.  Additional keyword arguments will be passed to the constructor of the
-   class.
+   kwarg; otherwise :class:`JSONDecoder` is used.  Additional keyword arguments
+   will be passed to the constructor of the class.
 
 
 .. function:: loads(s, encoding=None, cls=None, object_hook=None, parse_float=None, parse_int=None, parse_constant=None, object_pairs_hook=None, **kw)
@@ -275,6 +275,11 @@ Encoders and decoders
    ``'false'``.  This can be used to raise an exception if invalid JSON numbers
    are encountered.
 
+   If *strict* is ``False`` (``True`` is the default), then control characters
+   will be allowed inside strings.  Control characters in this context are
+   those with character codes in the 0-31 range, including ``'\t'`` (tab),
+   ``'\n'``, ``'\r'`` and ``'\0'``.
+
 
    .. method:: decode(s)
 

Lib/json/__init__.py

@@ -155,7 +155,7 @@ def dump(obj, fp, skipkeys=False, ensure_ascii=True, check_circular=True,
 
     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
     ``.default()`` method to serialize additional types), specify it with
-    the ``cls`` kwarg.
+    the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.
 
     """
     # cached encoder
@@ -213,7 +213,7 @@ def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
 
     To use a custom ``JSONEncoder`` subclass (e.g. one that overrides the
     ``.default()`` method to serialize additional types), specify it with
-    the ``cls`` kwarg.
+    the ``cls`` kwarg; otherwise ``JSONEncoder`` is used.
 
     """
     # cached encoder
@@ -244,8 +244,16 @@ def load(fp, cls=None, object_hook=None, parse_float=None,
     ``object_hook`` will be used instead of the ``dict``. This feature
     can be used to implement custom decoders (e.g. JSON-RPC class hinting).
 
+    ``object_pairs_hook`` is an optional function that will be called with the
+    result of any object literal decoded with an ordered list of pairs.  The
+    return value of ``object_pairs_hook`` will be used instead of the ``dict``.
+    This feature can be used to implement custom decoders that rely on the
+    order that the key and value pairs are decoded (for example,
+    collections.OrderedDict will remember the order of insertion). If
+    ``object_hook`` is also defined, the ``object_pairs_hook`` takes priority.
+
     To use a custom ``JSONDecoder`` subclass, specify it with the ``cls``
-    kwarg.
+    kwarg; otherwise ``JSONDecoder`` is used.
 
     """
     return loads(fp.read(),
@@ -264,6 +272,14 @@ def loads(s, encoding=None, cls=None, object_hook=None, parse_float=None,
     ``object_hook`` will be used instead of the ``dict``. This feature
     can be used to implement custom decoders (e.g. JSON-RPC class hinting).
 
+    ``object_pairs_hook`` is an optional function that will be called with the
+    result of any object literal decoded with an ordered list of pairs.  The
+    return value of ``object_pairs_hook`` will be used instead of the ``dict``.
+    This feature can be used to implement custom decoders that rely on the
+    order that the key and value pairs are decoded (for example,
+    collections.OrderedDict will remember the order of insertion). If
+    ``object_hook`` is also defined, the ``object_pairs_hook`` takes priority.
+
     ``parse_float``, if specified, will be called with the string
     of every JSON float to be decoded. By default this is equivalent to
     float(num_str). This can be used to use another datatype or parser
@@ -280,7 +296,7 @@ def loads(s, encoding=None, cls=None, object_hook=None, parse_float=None,
     are encountered.
 
     To use a custom ``JSONDecoder`` subclass, specify it with the ``cls``
-    kwarg.
+    kwarg; otherwise ``JSONDecoder`` is used.
 
     """
     if (cls is None and object_hook is None and

Lib/json/decoder.py

@@ -294,6 +294,15 @@ class JSONDecoder(object):
         place of the given ``dict``.  This can be used to provide custom
         deserializations (e.g. to support JSON-RPC class hinting).
 
+        ``object_pairs_hook``, if specified will be called with the result of
+        every JSON object decoded with an ordered list of pairs.  The return
+        value of ``object_pairs_hook`` will be used instead of the ``dict``.
+        This feature can be used to implement custom decoders that rely on the
+        order that the key and value pairs are decoded (for example,
+        collections.OrderedDict will remember the order of insertion). If
+        ``object_hook`` is also defined, the ``object_pairs_hook`` takes
+        priority.
+
         ``parse_float``, if specified, will be called with the string
         of every JSON float to be decoded. By default this is equivalent to
         float(num_str). This can be used to use another datatype or parser
@@ -309,6 +318,11 @@ class JSONDecoder(object):
         This can be used to raise an exception if invalid JSON numbers
         are encountered.
 
+        If ``strict`` is false (true is the default), then control
+        characters will be allowed inside strings.  Control characters in
+        this context are those with character codes in the 0-31 range,
+        including ``'\\t'`` (tab), ``'\\n'``, ``'\\r'`` and ``'\\0'``.
+
         """
         self.object_hook = object_hook
         self.parse_float = parse_float or float