[Python-checkins] r62736 - python/trunk/Doc/library/json.rst
georg.brandl
python-checkins at python.org
Mon May 5 22:53:40 CEST 2008
Author: georg.brandl
Date: Mon May 5 22:53:39 2008
New Revision: 62736
Log:
Fix JSON module docs.
Modified:
python/trunk/Doc/library/json.rst
Modified: python/trunk/Doc/library/json.rst
==============================================================================
--- python/trunk/Doc/library/json.rst (original)
+++ python/trunk/Doc/library/json.rst Mon May 5 22:53:39 2008
@@ -1,8 +1,8 @@
-:mod:`json` JSON encoder and decoder
-====================================
+:mod:`json` --- JSON encoder and decoder
+========================================
.. module:: json
- :synopsis: encode and decode the JSON format
+ :synopsis: Encode and decode the JSON format.
.. moduleauthor:: Bob Ippolito <bob at redivi.com>
.. sectionauthor:: Bob Ippolito <bob at redivi.com>
.. versionadded:: 2.6
@@ -10,8 +10,8 @@
JSON (JavaScript Object Notation) <http://json.org> is a subset of JavaScript
syntax (ECMA-262 3rd edition) used as a lightweight data interchange format.
-:mod:`json` exposes an API familiar to uses of the standard library marshal and
-pickle modules.
+:mod:`json` exposes an API familiar to users of the standard library
+:mod:`marshal` and :mod:`pickle` modules.
Encoding basic Python object hierarchies::
@@ -74,7 +74,7 @@
>>> json.loads('1.1', parse_float=decimal.Decimal)
Decimal('1.1')
-Extending JSONEncoder::
+Extending :class:`JSONEncoder`::
>>> import json
>>> class ComplexEncoder(json.JSONEncoder):
@@ -106,7 +106,7 @@
.. note::
- Note that the JSON produced by this module's default settings is a subset of
+ The JSON produced by this module's default settings is a subset of
YAML, so it may be used as a serializer for that as well.
@@ -115,139 +115,104 @@
.. function:: dump(obj, fp[, skipkeys[, ensure_ascii[, check_circular[, allow_nan[, cls[, indent[, separators[, encoding[, default[, **kw]]]]]]]]]])
- Serialize *obj* as a JSON formatted stream to *fp* (a
- ``.write()``-supporting file-like object).
+ Serialize *obj* as a JSON formatted stream to *fp* (a ``.write()``-supporting
+ file-like object).
- If *skipkeys* is ``True`` (It is ``False`` by default.), then ``dict`` keys
- that are not basic types (``str``, ``unicode``, ``int``, ``long``,
- ``float``, ``bool``, ``None``) will be skipped instead of raising a
- :exc:`TypeError`.
+ If *skipkeys* is ``True`` (default: ``False``), then dict keys that are not
+ of a basic type (:class:`str`, :class:`unicode`, :class:`int`, :class:`long`,
+ :class:`float`, :class:`bool`, ``None``) will be skipped instead of raising a
+ :exc:`TypeError`.
- If *ensure_ascii* is ``False`` (It is ``True`` by default.), then the some
- chunks written to *fp* may be ``unicode`` instances, subject to normal
- Python ``str`` to ``unicode`` coercion rules. Unless ``fp.write()``
- explicitly understands ``unicode`` (as in ``codecs.getwriter()``) this is
- likely to cause an error.
+ If *ensure_ascii* is ``False`` (default: ``True``), then some chunks written
+ to *fp* may be :class:`unicode` instances, subject to normal Python
+ :class:`str` to :class:`unicode` coercion rules. Unless ``fp.write()``
+ explicitly understands :class:`unicode` (as in :func:`codecs.getwriter`) this
+ is likely to cause an error.
- If *check_circular* is ``False``, then the circular reference check for
- container types will be skipped and a circular reference will result in an
- :exc:`OverflowError` (or worse).
+ If *check_circular* is ``False`` (default: ``True``), then the circular
+ reference check for container types will be skipped and a circular reference
+ will result in an :exc:`OverflowError` (or worse).
- If *allow_nan* is ``False``, then it will be a :exc:`ValueError` to
- serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in
- strict compliance of the JSON specification, instead of using the JavaScript
- equivalents (``NaN``, ``Infinity``, ``-Infinity``).
+ If *allow_nan* is ``False`` (default: ``True``), then it will be a
+ :exc:`ValueError` to serialize out of range :class:`float` values (``nan``,
+ ``inf``, ``-inf``) in strict compliance of the JSON specification, instead of
+ using the JavaScript equivalents (``NaN``, ``Infinity``, ``-Infinity``).
- If *indent* is a non-negative integer, then JSON array elements and object
- members will be pretty-printed with that indent level. An indent level of 0
- will only insert newlines. ``None`` is the most compact representation.
+ If *indent* is a non-negative integer, then JSON array elements and object
+ members will be pretty-printed with that indent level. An indent level of 0
+ will only insert newlines. ``None`` (the default) selects the most compact
+ representation.
- If *separators* is an ``(item_separator, dict_separator)`` tuple then it
- will be used instead of the default ``(', ', ': ')`` separators. ``(',',
- ':')`` is the most compact JSON representation.
+ If *separators* is an ``(item_separator, dict_separator)`` tuple, then it
+ will be used instead of the default ``(', ', ': ')`` separators. ``(',',
+ ':')`` is the most compact JSON representation.
- *encoding* is the character encoding for str instances, default is UTF-8.
+ *encoding* is the character encoding for str instances, default is UTF-8.
- *default(obj)* is a function that should return a serializable version of
- obj or raise :exc:`TypeError`. The default simply raises :exc:`TypeError`.
+ *default(obj)* is a function that should return a serializable version of
+ *obj* or raise :exc:`TypeError`. The default simply raises :exc:`TypeError`.
- To use a custom :class:`JSONEncoder`` subclass (e.g. one that overrides the
- ``.default()`` method to serialize additional types), specify it with the
- *cls* kwarg.
+ 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.
-.. function:: dump(obj[, skipkeys[, ensure_ascii[, check_circular[, allow_nan[, cls[, indent[, separators[, encoding[, default[, **kw]]]]]]]]]])
+.. function:: dumps(obj[, skipkeys[, ensure_ascii[, check_circular[, allow_nan[, cls[, indent[, separators[, encoding[, default[, **kw]]]]]]]]]])
- Serialize *obj* to a JSON formatted ``str``.
+ Serialize *obj* to a JSON formatted :class:`str`.
- If *skipkeys* is ``True`` (It is ``False`` by default.), then ``dict`` keys
- that are not basic types (``str``, ``unicode``, ``int``, ``long``,
- ``float``, ``bool``, ``None``) will be skipped instead of raising a
- :exc:`TypeError`.
+ If *ensure_ascii* is ``False``, then the return value will be a
+ :class:`unicode` instance. The other arguments have the same meaning as in
+ :func:`dump`.
- If *ensure_ascii* is ``False``, then the return value will be a ``unicode``
- instance subject to normal Python ``str`` to ``unicode`` coercion rules
- instead of being escaped to an ASCII ``str``.
- If *check_circular* is ``False``, then the circular reference check for
- container types will be skipped and a circular reference will result in an
- :exc:`OverflowError` (or worse).
-
- If *allow_nan* is ``False``, then it will be a :exc:`ValueError` to
- serialize out of range ``float`` values (``nan``, ``inf``, ``-inf``) in
- strict compliance of the JSON specification, instead of using the JavaScript
- equivalents (``NaN``, ``Infinity``, ``-Infinity``).
-
- If *indent* is a non-negative integer, then JSON array elements and object
- members will be pretty-printed with that indent level. An indent level of 0
- will only insert newlines. ``None`` is the most compact representation.
-
- If *separators* is an ``(item_separator, dict_separator)`` tuple then it
- will be used instead of the default ``(', ', ': ')`` separators. ``(',',
- ':')`` is the most compact JSON representation.
-
- *encoding* is the character encoding for str instances, default is UTF-8.
-
- *default(obj)* is a function that should return a serializable version of
- obj or raise :exc:`TypeError`. The default simply raises :exc:`TypeError`.
-
- To use a custom :class:`JSONEncoder`` subclass (e.g. one that overrides the
- ``.default()`` method to serialize additional types), specify it with the
- *cls* kwarg.
-
-
-.. function loads(s[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
+.. function load(fp[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
- Deserialize *s* (a ``str`` or ``unicode`` instance containing a JSON
+ Deserialize *fp* (a ``.read()``-supporting file-like object containing a JSON
document) to a Python object.
- If *s* is a ``str`` instance and is encoded with an ASCII based encoding
- other than utf-8 (e.g. latin-1) then an appropriate ``encoding`` name must be
- specified. Encodings that are not ASCII based (such as UCS-2) are not allowed
- and should be decoded to ``unicode`` first.
+ If the contents of *fp* are encoded with an ASCII based encoding other than
+ UTF-8 (e.g. latin-1), then an appropriate *encoding* name must be specified.
+ Encodings that are not ASCII based (such as UCS-2) are not allowed, and
+ should be wrapped with ``codecs.getreader(fp)(encoding)``, or simply decoded
+ to a :class:`unicode` object and passed to :func:`loads`.
*object_hook* is an optional function that will be called with the result of
- any object literal decode (a ``dict``). The return value of ``object_hook``
- will be used instead of the ``dict``. This feature can be used to implement
- custom decoders (e.g. JSON-RPC class hinting).
+ any object literal decode (a :class:`dict`). The return value of
+ *object_hook* will be used instead of the :class:`dict`. This feature can be used
+ to implement custom decoders (e.g. JSON-RPC class hinting).
*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 for
- JSON floats (e.g. decimal.Decimal).
+ float to be decoded. By default, this is equivalent to ``float(num_str)``.
+ This can be used to use another datatype or parser for JSON floats
+ (e.g. :class:`decimal.Decimal`).
*parse_int*, if specified, will be called with the string of every JSON int
- to be decoded. By default this is equivalent to int(num_str). This can be
- used to use another datatype or parser for JSON integers (e.g. float).
+ to be decoded. By default, this is equivalent to ``int(num_str)``. This can
+ be used to use another datatype or parser for JSON integers
+ (e.g. :class:`float`).
*parse_constant*, if specified, will be called with one of the following
- strings: -Infinity, Infinity, NaN, null, true, false. This can be used to
- raise an exception if invalid JSON numbers are encountered.
+ strings: ``'-Infinity'``, ``'Infinity'``, ``'NaN'``, ``'null'``, ``'true'``,
+ ``'false'``. This can be used to raise an exception if invalid JSON numbers
+ 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
+ kwarg. Additional keyword arguments will be passed to the constructor of the
class.
-.. function load(fp[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
+.. function loads(s[, encoding[, cls[, object_hook[, parse_float[, parse_int[, parse_constant[, **kw]]]]]]])
- Deserialize *fp* (a ``.read()``-supporting file-like object containing a JSON
+ Deserialize *s* (a :class:`str` or :class:`unicode` instance containing a JSON
document) to a Python object.
- If the contents of *fp* is encoded with an ASCII based encoding other than
- utf-8 (e.g. latin-1), then an appropriate ``encoding`` name must be
- specified. Encodings that are not ASCII based (such as UCS-2) are not
- allowed, and should be wrapped with :func:`codecs.getreader(fp)(encoding)`,
- or simply decoded to a ``unicode`` object and passed to ``loads()``
+ If *s* is a :class:`str` instance and is encoded with an ASCII based encoding
+ other than UTF-8 (e.g. latin-1), then an appropriate *encoding* name must be
+ specified. Encodings that are not ASCII based (such as UCS-2) are not
+ allowed and should be decoded to :class:`unicode` first.
- *object_hook* is an optional function that will be called with the result of
- any object literal decode (a ``dict``). The return value of *object_hook*
- will be used instead of the ``dict``. This feature can be used to implement
- custom decoders (e.g. JSON-RPC class hinting).
-
- 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.
+ The other arguments have the same meaning as in :func:`dump`.
Encoders and decoders
@@ -255,7 +220,7 @@
.. class:: JSONDecoder([encoding[, object_hook[, parse_float[, parse_int[, parse_constant[, strict]]]]]])
- Simple JSON decoder
+ Simple JSON decoder.
Performs the following translations in decoding by default:
@@ -282,50 +247,52 @@
It also understands ``NaN``, ``Infinity``, and ``-Infinity`` as their
corresponding ``float`` values, which is outside the JSON spec.
- *encoding* determines the encoding used to interpret any ``str`` objects
- decoded by this instance (utf-8 by default). It has no effect when decoding
- ``unicode`` objects.
+ *encoding* determines the encoding used to interpret any :class:`str` objects
+ decoded by this instance (UTF-8 by default). It has no effect when decoding
+ :class:`unicode` objects.
- Note that currently only encodings that are a superset of ASCII work,
- strings of other encodings should be passed in as ``unicode``.
+ Note that currently only encodings that are a superset of ASCII work, strings
+ of other encodings should be passed in as :class:`unicode`.
*object_hook*, if specified, will be called with the result of every JSON
object decoded and its return value will be used in place of the given
- ``dict``. This can be used to provide custom deserializations (e.g. to
+ :class:`dict`. This can be used to provide custom deserializations (e.g. to
support JSON-RPC class hinting).
*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 for JSON floats
- (e.g. decimal.Decimal).
+ float to be decoded. By default, this is equivalent to ``float(num_str)``.
+ This can be used to use another datatype or parser for JSON floats
+ (e.g. :class:`decimal.Decimal`).
*parse_int*, if specified, will be called with the string of every JSON int
- to be decoded. By default this is equivalent to int(num_str). This can be
- used to use another datatype or parser for JSON integers (e.g. float).
+ to be decoded. By default, this is equivalent to ``int(num_str)``. This can
+ be used to use another datatype or parser for JSON integers
+ (e.g. :class:`float`).
*parse_constant*, if specified, will be called with one of the following
- strings: -Infinity, Infinity, NaN, null, true, false. This can be used to
- raise an exception if invalid JSON numbers are encountered.
+ strings: ``'-Infinity'``, ``'Infinity'``, ``'NaN'``, ``'null'``, ``'true'``,
+ ``'false'``. This can be used to raise an exception if invalid JSON numbers
+ are encountered.
.. method:: decode(s)
- Return the Python representation of *s* (a ``str`` or ``unicode`` instance
- containing a JSON document)
+ Return the Python representation of *s* (a :class:`str` or
+ :class:`unicode` instance containing a JSON document)
.. method:: raw_decode(s)
- Decode a JSON document from *s* (a ``str`` or ``unicode`` beginning with a
- JSON document) and return a 2-tuple of the Python representation and the
- index in *s* where the document ended.
+ Decode a JSON document from *s* (a :class:`str` or :class:`unicode`
+ beginning with a JSON document) and return a 2-tuple of the Python
+ representation and the index in *s* where the document ended.
- This can be used to decode a JSON document from a string that may have
- extraneous data at the end.
+ This can be used to decode a JSON document from a string that may have
+ extraneous data at the end.
.. class:: JSONEncoder([skipkeys[, ensure_ascii[, check_circular[, allow_nan[, sort_keys[, indent[, separators[, encoding[, default]]]]]]]]])
- Extensible JSON <http://json.org> encoder for Python data structures.
+ Extensible JSON encoder for Python data structures.
Supports the following objects and types by default:
@@ -348,7 +315,7 @@
+-------------------+---------------+
To extend this to recognize other objects, subclass and implement a
- ``.default()`` method with another method that returns a serializable object
+ :meth:`default` method with another method that returns a serializable object
for ``o`` if possible, otherwise it should call the superclass implementation
(to raise :exc:`TypeError`).
@@ -356,31 +323,32 @@
attempt encoding of keys that are not str, int, long, float or None. If
*skipkeys* is ``True``, such items are simply skipped.
- If *ensure_ascii* is ``True``, the output is guaranteed to be ``str`` objects
- with all incoming unicode characters escaped. If *ensure_ascii* is
- ``False``, the output will be unicode object.
+ If *ensure_ascii* is ``True`` (the default), the output is guaranteed to be
+ :class:`str` objects with all incoming unicode characters escaped. If
+ *ensure_ascii* is ``False``, the output will be a unicode object.
If *check_circular* is ``True`` (the default), then lists, dicts, and custom
encoded objects will be checked for circular references during encoding to
prevent an infinite recursion (which would cause an :exc:`OverflowError`).
Otherwise, no such check takes place.
- If *allow_nan* is ``True`` (the default), then ``NaN``, ``Infinity``, and ``-Infinity``
- will be encoded as such. This behavior is not JSON specification compliant,
- but is consistent with most JavaScript based encoders and decoders.
- Otherwise, it will be a :exc:`ValueError` to encode such floats.
+ If *allow_nan* is ``True`` (the default), then ``NaN``, ``Infinity``, and
+ ``-Infinity`` will be encoded as such. This behavior is not JSON
+ specification compliant, but is consistent with most JavaScript based
+ encoders and decoders. Otherwise, it will be a :exc:`ValueError` to encode
+ such floats.
If *sort_keys* is ``True`` (the default), then the output of dictionaries
will be sorted by key; this is useful for regression tests to ensure that
JSON serializations can be compared on a day-to-day basis.
- If *indent* is a non-negative integer (It is ``None`` by default.), then JSON
+ If *indent* is a non-negative integer (it is ``None`` by default), then JSON
array elements and object members will be pretty-printed with that indent
level. An indent level of 0 will only insert newlines. ``None`` is the most
compact representation.
- If specified, *separators* should be a (item_separator, key_separator) tuple.
- The default is ``(', ', ': ')``. To get the most compact JSON
+ If specified, *separators* should be an ``(item_separator, key_separator)``
+ tuple. The default is ``(', ', ': ')``. To get the most compact JSON
representation, you should specify ``(',', ':')`` to eliminate whitespace.
If specified, *default* is a function that gets called for objects that can't
@@ -413,7 +381,7 @@
.. method:: encode(o)
- Return a JSON string representation of a Python data structure, *o*. For
+ Return a JSON string representation of a Python data structure, *o*. For
example::
>>> JSONEncoder().encode({"foo": ["bar", "baz"]})
@@ -423,9 +391,7 @@
.. method:: iterencode(o)
Encode the given object, *o*, and yield each string representation as
- available.
-
- For example::
+ available. For example::
for chunk in JSONEncoder().iterencode(bigobject):
mysocket.write(chunk)
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