whatsnew: XMLPullParser, plus some doc updates.
I was confused by the text saying that read_events "iterated", since it
actually returns an iterator (that's what a generator does) that the
caller must then iterate. So I tidied up the language. I'm not sure
what the sentence "Events provided in a previous call to read_events()
will not be yielded again." is trying to convey, so I didn't try to fix that.
Also fixed a couple more news items.
diff --git a/Doc/library/xml.etree.elementtree.rst b/Doc/library/xml.etree.elementtree.rst
index 0731cd8..fb6da15 100644
--- a/Doc/library/xml.etree.elementtree.rst
+++ b/Doc/library/xml.etree.elementtree.rst
@@ -105,12 +105,15 @@
>>> root[0][1].text
'2008'
+
+.. _elementtree-pull-parsing:
+
Pull API for non-blocking parsing
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-Most parsing functions provided by this module require to read the whole
-document at once before returning any result. It is possible to use a
-:class:`XMLParser` and feed data into it incrementally, but it's a push API that
+Most parsing functions provided by this module require the whole document
+to be read at once before returning any result. It is possible to use an
+:class:`XMLParser` and feed data into it incrementally, but it is a push API that
calls methods on a callback target, which is too low-level and inconvenient for
most needs. Sometimes what the user really wants is to be able to parse XML
incrementally, without blocking operations, while enjoying the convenience of
@@ -119,7 +122,7 @@
The most powerful tool for doing this is :class:`XMLPullParser`. It does not
require a blocking read to obtain the XML data, and is instead fed with data
incrementally with :meth:`XMLPullParser.feed` calls. To get the parsed XML
-elements, call :meth:`XMLPullParser.read_events`. Here's an example::
+elements, call :meth:`XMLPullParser.read_events`. Here is an example::
>>> parser = ET.XMLPullParser(['start', 'end'])
>>> parser.feed('<mytag>sometext')
@@ -1038,15 +1041,17 @@
.. method:: read_events()
- Iterate over the events which have been encountered in the data fed to the
- parser. This method yields ``(event, elem)`` pairs, where *event* is a
+ Return an iterator over the events which have been encountered in the
+ data fed to the
+ parser. The iterator yields ``(event, elem)`` pairs, where *event* is a
string representing the type of event (e.g. ``"end"``) and *elem* is the
encountered :class:`Element` object.
Events provided in a previous call to :meth:`read_events` will not be
- yielded again. As events are consumed from the internal queue only as
- they are retrieved from the iterator, multiple readers calling
- :meth:`read_events` in parallel will have unpredictable results.
+ yielded again. Events are consumed from the internal queue only when
+ they are retrieved from the iterator, so multiple readers iterating in
+ parallel over iterators obtained from :meth:`read_events` will have
+ unpredictable results.
.. note::
diff --git a/Doc/whatsnew/3.4.rst b/Doc/whatsnew/3.4.rst
index ab48020..f954f12 100644
--- a/Doc/whatsnew/3.4.rst
+++ b/Doc/whatsnew/3.4.rst
@@ -1088,9 +1088,10 @@
xml.etree
---------
-Add an event-driven parser for non-blocking applications,
-:class:`~xml.etree.ElementTree.XMLPullParser`.
-(Contributed by Antoine Pitrou in :issue:`17741`.)
+A new parser, :class:`~xml.etree.ElementTree.XMLPullParser`, allows a
+non-blocking applications to parse XML documents. An example can be
+seen at :ref:`elementtree-pull-parsing`. (Contributed by Antoine
+Pitrou in :issue:`17741`.)
The :mod:`xml.etree.ElementTree` :func:`~xml.etree.ElementTree.tostring` and
:func:`~xml.etree.ElementTree.tostringlist` functions, and the
diff --git a/Lib/xml/etree/ElementTree.py b/Lib/xml/etree/ElementTree.py
index cab415c..d9e9807 100644
--- a/Lib/xml/etree/ElementTree.py
+++ b/Lib/xml/etree/ElementTree.py
@@ -1251,7 +1251,7 @@
self._close_and_return_root()
def read_events(self):
- """Iterate over currently available (event, elem) pairs.
+ """Return an iterator over currently available (event, elem) pairs.
Events are consumed from the internal event queue as they are
retrieved from the iterator.
diff --git a/Misc/NEWS b/Misc/NEWS
index a640295..0e59d0f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -2193,14 +2193,14 @@
- Issue #17555: Fix ForkAwareThreadLock so that size of after fork
registry does not grow exponentially with generation of process.
-- Issue #17707: multiprocessing.Queue's get() method does not block for short
- timeouts.
+- Issue #17707: fix regression in multiprocessing.Queue's get() method where
+ it did not block for short timeouts.
-- Isuse #17720: Fix the Python implementation of pickle.Unpickler to correctly
+- Issue #17720: Fix the Python implementation of pickle.Unpickler to correctly
process the APPENDS opcode when it is used on non-list objects.
-- Issue #17012: shutil.which() no longer fallbacks to the PATH environment
- variable if empty path argument is specified. Patch by Serhiy Storchaka.
+- Issue #17012: shutil.which() no longer falls back to the PATH environment
+ variable if an empty path argument is specified. Patch by Serhiy Storchaka.
- Issue #17710: Fix pickle raising a SystemError on bogus input.