[Python-checkins] r88077 - python/branches/py3k/Doc/whatsnew/3.2.rst
raymond.hettinger
python-checkins at python.org
Tue Jan 18 00:10:55 CET 2011
Author: raymond.hettinger
Date: Tue Jan 18 00:10:55 2011
New Revision: 88077
Log:
Beautify code examples.
Modified:
python/branches/py3k/Doc/whatsnew/3.2.rst
Modified: python/branches/py3k/Doc/whatsnew/3.2.rst
==============================================================================
--- python/branches/py3k/Doc/whatsnew/3.2.rst (original)
+++ python/branches/py3k/Doc/whatsnew/3.2.rst Tue Jan 18 00:10:55 2011
@@ -208,10 +208,10 @@
If that dictionary is stored in a file called :file:`conf.json`, it can be
loaded and called with code like this::
- >>> import logging.config
- >>> logging.config.dictConfig(json.load(open('conf.json', 'rb')))
- >>> logging.info("Transaction completed normally")
- >>> logging.critical("Abnormal termination")
+ import logging.config
+ logging.config.dictConfig(json.load(open('conf.json', 'rb')))
+ logging.info("Transaction completed normally")
+ logging.critical("Abnormal termination")
.. seealso::
@@ -482,24 +482,24 @@
* Previously it was illegal to delete a name from the local namespace if it
occurs as a free variable in a nested block::
- >>> def outer(x):
- ... def inner():
- ... return x
- ... inner()
- ... del x
+ def outer(x):
+ def inner():
+ return x
+ inner()
+ del x
This is now allowed. Remember that the target of an :keyword:`except` clause
is cleared, so this code which used to work with Python 2.6, raised a
:exc:`SyntaxError` with Python 3.1 and now works again::
- >>> def f():
- ... def print_error():
- ... print(e)
- ... try:
- ... something
- ... except Exception as e:
- ... print_error()
- ... # implicit "del e" here
+ def f():
+ def print_error():
+ print(e)
+ try:
+ something
+ except Exception as e:
+ print_error()
+ # implicit "del e" here
(See :issue:`4617`.)
@@ -598,7 +598,7 @@
*SSL* connections and security certificates.
In addition, more classes now implement a :term:`context manager` to support
-convenient and reliable resource clean-up using the :keyword:`with`-statement.
+convenient and reliable resource clean-up using the :keyword:`with` statement.
email
-----
@@ -682,16 +682,16 @@
resource whenever the results are expected to be the same.
For example, adding a caching decorator to a database query function can save
- database accesses for popular searches::
+ database accesses for popular searches:
- @functools.lru_cache(maxsize=300)
- def get_phone_number(name):
- c = conn.cursor()
- c.execute('SELECT phonenumber FROM phonelist WHERE name=?', (name,))
- return c.fetchone()[0]
+ >>> @functools.lru_cache(maxsize=300)
+ >>> def get_phone_number(name):
+ c = conn.cursor()
+ c.execute('SELECT phonenumber FROM phonelist WHERE name=?', (name,))
+ return c.fetchone()[0]
>>> for name in user_requests:
- ... get_phone_number(name) # cached lookup
+ get_phone_number(name) # cached lookup
To help with choosing an effective cache size, the wrapped function is
instrumented for tracking cache statistics:
@@ -928,7 +928,7 @@
The basic idea is that both context managers and function decorators can be used
for pre-action and post-action wrappers. Context managers wrap a group of
-statements using the :keyword:`with`-statement, and function decorators wrap a
+statements using the :keyword:`with` statement, and function decorators wrap a
group of statements enclosed in a function. So, occasionally there is a need to
write a pre-action or post-action wrapper that can be used in either role.
@@ -936,32 +936,32 @@
with a logger that can track the time of entry and time of exit. Rather than
writing both a function decorator and a context manager for the task, the
:func:`~contextlib.contextmanager` provides both capabilities in a single
-definition:
+definition::
->>> import logging
->>> logging.basicConfig(level=logging.INFO)
->>> @contextmanager
-... def track_entry_and_exit(name):
-... logging.info('Entering: {}'.format(name))
-... yield
-... logging.info('Exiting: {}'.format(name))
-
-Formerly, this would have only been usable as a context manager:
-
->>> with track_entry_and_exit('widget loader'):
-... print('Some time consuming activity goes here')
-... load_widget()
-
-Now, it can be used as a decorator as well:
-
->>> @track_entry_and_exit('widget loader')
-... def activity():
-... print('Some time consuming activity goes here')
-... load_widget()
+ import logging
+ logging.basicConfig(level=logging.INFO)
+ @contextmanager
+ def track_entry_and_exit(name):
+ logging.info('Entering: {}'.format(name))
+ yield
+ logging.info('Exiting: {}'.format(name))
+
+Formerly, this would have only been usable as a context manager::
+
+ with track_entry_and_exit('widget loader'):
+ print('Some time consuming activity goes here')
+ load_widget()
+
+Now, it can be used as a decorator as well::
+
+ @track_entry_and_exit('widget loader')
+ def activity():
+ print('Some time consuming activity goes here')
+ load_widget()
Trying to fulfill two roles at once places some limitations on the technique.
Context managers normally have the flexibility to return an argument usable by
-the :keyword:`with`-statement, but there is no parallel for function decorators.
+the :keyword:`with` statement, but there is no parallel for function decorators.
In the above example, there is not a clean way for the *track_entry_and_exit*
context manager to return a logging instance for use in the body of enclosed
@@ -976,8 +976,8 @@
different numeric datatypes will have the same hash value whenever their actual
values are equal (:issue:`8188`)::
- >>> assert hash(Fraction(3, 2)) == hash(1.5) == \
- hash(Decimal("1.5")) == hash(complex(1.5, 0))
+ assert hash(Fraction(3, 2)) == hash(1.5) == \
+ hash(Decimal("1.5")) == hash(complex(1.5, 0))
An early decision to limit the inter-operability of various numeric types has
been relaxed. It is still unsupported (and ill-advised) to to have implicit
@@ -1235,10 +1235,10 @@
* The :mod:`unittest` module has two new methods,
:meth:`~unittest.TestCase.assertWarns` and
:meth:`~unittest.TestCase.assertWarnsRegex` to verify that a given warning type
- is triggered by the code under test:
+ is triggered by the code under test::
- >>> with self.assertWarns(DeprecationWarning):
- ... legacy_function('XYZ')
+ with self.assertWarns(DeprecationWarning):
+ legacy_function('XYZ')
(Contributed by Antoine Pitrou, :issue:`9754`.)
@@ -1331,10 +1331,10 @@
The :mod:`tempfile` module has a new context manager,
:class:`~tempfile.TemporaryDirectory` which provides easy deterministic
-cleanup of temporary directories:
+cleanup of temporary directories::
->>> with tempfile.TemporaryDirectory() as tmpdirname:
-... print('created temporary dir:', tmpdirname)
+ with tempfile.TemporaryDirectory() as tmpdirname:
+ print('created temporary dir:', tmpdirname)
(Contributed by Neil Schemenauer and Nick Coghlan; :issue:`5178`.)
@@ -1456,13 +1456,13 @@
>>> parser = ConfigParser()
>>> parser.read_string("""
- ... [DEFAULT]
- ... monty = python
- ...
- ... [phrases]
- ... the = who
- ... full = metal jacket
- ... """)
+ [DEFAULT]
+ monty = python
+
+ [phrases]
+ the = who
+ full = metal jacket
+ """)
>>> parser['phrases']['full']
'metal jacket'
>>> section = parser['phrases']
@@ -1485,24 +1485,24 @@
>>> parser = ConfigParser(interpolation=ExtendedInterpolation())
>>> parser.read_dict({'buildout': {'directory': '/home/ambv/zope9'},
- ... 'custom': {'prefix': '/usr/local'}})
+ 'custom': {'prefix': '/usr/local'}})
>>> parser.read_string("""
- ... [buildout]
- ... parts =
- ... zope9
- ... instance
- ... find-links =
- ... ${buildout:directory}/downloads/dist
- ...
- ... [zope9]
- ... recipe = plone.recipe.zope9install
- ... location = /opt/zope
- ...
- ... [instance]
- ... recipe = plone.recipe.zope9instance
- ... zope9-location = ${zope9:location}
- ... zope-conf = ${custom:prefix}/etc/zope.conf
- ... """)
+ [buildout]
+ parts =
+ zope9
+ instance
+ find-links =
+ ${buildout:directory}/downloads/dist
+
+ [zope9]
+ recipe = plone.recipe.zope9install
+ location = /opt/zope
+
+ [instance]
+ recipe = plone.recipe.zope9instance
+ zope9-location = ${zope9:location}
+ zope-conf = ${custom:prefix}/etc/zope.conf
+ """)
>>> parser['buildout']['find-links']
'\n/home/ambv/zope9/downloads/dist'
>>> parser['instance']['zope-conf']
@@ -1876,10 +1876,10 @@
and it does a better job finalizing multiple context managers when one of them
raises an exception::
- >>> with open('mylog.txt') as infile, open('a.out', 'w') as outfile:
- ... for line in infile:
- ... if '<critical>' in line:
- ... outfile.write(line)
+ with open('mylog.txt') as infile, open('a.out', 'w') as outfile:
+ for line in infile:
+ if '<critical>' in line:
+ outfile.write(line)
(Contributed by Georg Brandl and Mattias Brändström;
`appspot issue 53094 <http://codereview.appspot.com/53094>`_.)
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