-----------
Literal code blocks are introduced by ending a paragraph with the special marker
-``::``. The literal block must be indented, to be able to include blank lines::
+``::``. The literal block must be indented::
This is a normal text paragraph. The next paragraph is a code sample::
def f(...):
...
- The same concept exists for classes, but is less commonly used there.
+ The same concept exists for classes, but is less commonly used there. See
+ the documentation for :ref:`function definitions <function>` and
+ :ref:`class definitions <class>` for more about decorators.
descriptor
Any object which defines the methods :meth:`__get__`, :meth:`__set__`, or
when several are given, such as in ``variable_name[1:3:5]``. The bracket
(subscript) notation uses :class:`slice` objects internally.
+ special method
+ A method that is called implicitly by Python to execute a certain
+ operation on a type, such as addition. Such methods have names starting
+ and ending with double underscores. Special methods are documented in
+ :ref:`specialnames`.
+
statement
A statement is part of a suite (a "block" of code). A statement is either
an :term:`expression` or a one of several constructs with a keyword, such
non-option argument is encountered.
If the first character of the option string is '+', or if the environment
- variable POSIXLY_CORRECT is set, then option processing stops as soon as a
- non-option argument is encountered.
+ variable :envvar:`POSIXLY_CORRECT` is set, then option processing stops as
+ soon as a non-option argument is encountered.
.. exception:: GetoptError
>>> data == ordered
True
+Using a heap to insert items at the correct place in a priority queue:
+
+ >>> heap = []
+ >>> data = [(1, 'J'), (4, 'N'), (3, 'H'), (2, 'O')]
+ >>> for item in data:
+ ... heappush(heap, item)
+ ...
+ >>> while heap:
+ ... print(heappop(heap)[1])
+ J
+ O
+ H
+ N
+
+
The module also offers three general purpose functions based on heaps.
:func:`fdopen`, or :data:`sys.stdout` or :data:`sys.stderr`, use its :meth:`write`
method.
-The following data items are available for use in constructing the *flags*
-parameter to the :func:`open` function. Some items will not be available on all
-platforms. For descriptions of their availability and use, consult
-:manpage:`open(2)`.
+The following constants are options for the *flags* parameter to the
+:func:`open` function. They can be combined using the bitwise OR operator
+``|``. Some of them are not available on all platforms. For descriptions of
+their availability and use, consult the :manpage:`open(2)` manual page on Unix
+or `the MSDN <http://msdn.microsoft.com/en-us/library/z0kc8e3z.aspx>` on Windows.
.. data:: O_RDONLY
O_EXCL
O_TRUNC
- Options for the *flag* argument to the :func:`open` function. These can be
- combined using the bitwise OR operator ``|``. Availability: Unix, Windows.
+ These constants are available on Unix and Windows.
.. data:: O_DSYNC
O_SHLOCK
O_EXLOCK
- More options for the *flag* argument to the :func:`open` function. Availability:
- Unix.
+ These constants are only available on Unix.
.. data:: O_BINARY
O_SEQUENTIAL
O_TEXT
- Options for the *flag* argument to the :func:`open` function. These can be
- combined using the bitwise OR operator ``|``. Availability: Windows.
+ These constants are only available on Windows.
.. data:: O_ASYNC
O_NOFOLLOW
O_NOATIME
- Options for the *flag* argument to the :func:`open` function. These are
- GNU extensions and not present if they are not defined by the C library.
+ These constants are GNU extensions and not present if they are not defined by
+ the C library.
.. data:: SEEK_SET
were provided.
+.. attribute:: RegexObject.groups
+
+ The number of capturing groups in the pattern.
+
+
.. attribute:: RegexObject.groupindex
A dictionary mapping any symbolic group names defined by ``(?P<id>)`` to group
Copy the contents (no metadata) of the file named *src* to a file named *dst*.
*dst* must be the complete target file name; look at :func:`copy` for a copy that
- accepts a target directory path.
+ accepts a target directory path. If *src* and *dst* are the same files,
+ :exc:`Error` is raised.
The destination location must be writable; otherwise, an :exc:`IOError` exception
will be raised. If *dst* already exists, it will be replaced. Special files
such as character or block devices and pipes cannot be copied with this
specified by the :envvar:`COMSPEC` environment variable.
*stdin*, *stdout* and *stderr* specify the executed programs' standard input,
- standard output and standard error file handles, respectively. Valid values are
- ``PIPE``, an existing file descriptor (a positive integer), an existing file
- object, and ``None``. ``PIPE`` indicates that a new pipe to the child should be
- created. With ``None``, no redirection will occur; the child's file handles
- will be inherited from the parent. Additionally, *stderr* can be ``STDOUT``,
- which indicates that the stderr data from the applications should be captured
- into the same file handle as for stdout.
+ standard output and standard error file handles, respectively. Valid values
+ are :data:`PIPE`, an existing file descriptor (a positive integer), an
+ existing file object, and ``None``. :data:`PIPE` indicates that a new pipe
+ to the child should be created. With ``None``, no redirection will occur;
+ the child's file handles will be inherited from the parent. Additionally,
+ *stderr* can be :data:`STDOUT`, which indicates that the stderr data from the
+ applications should be captured into the same file handle as for stdout.
If *preexec_fn* is set to a callable object, this object will be called in the
child process just before the child is executed. (Unix only)
of the main window and priority for the new process. (Windows only)
+.. data:: PIPE
+
+ Special value that can be used as the *stdin*, *stdout* or *stderr* argument
+ to :class:`Popen` and indicates that a pipe to the standard stream should be
+ opened.
+
+
+.. data:: STDOUT
+
+ Special value that can be used as the *stderr* argument to :class:`Popen` and
+ indicates that standard error should go into the same handle as standard
+ output.
+
+
Convenience Functions
^^^^^^^^^^^^^^^^^^^^^
*input* argument should be a byte string to be sent to the child process, or
``None``, if no data should be sent to the child.
- :meth:`communicate` returns a tuple ``(stdout, stderr)``.
+ :meth:`communicate` returns a tuple ``(stdoutdata, stderrdata)``.
Note that if you want to send data to the process's stdin, you need to create
the Popen object with ``stdin=PIPE``. Similarly, to get anything other than
.. attribute:: Popen.stdin
- If the *stdin* argument is ``PIPE``, this attribute is a file object that
- provides input to the child process. Otherwise, it is ``None``.
+ If the *stdin* argument was :data:`PIPE`, this attribute is a file object
+ that provides input to the child process. Otherwise, it is ``None``.
.. attribute:: Popen.stdout
- If the *stdout* argument is ``PIPE``, this attribute is a file object that
- provides output from the child process. Otherwise, it is ``None``.
+ If the *stdout* argument was :data:`PIPE`, this attribute is a file object
+ that provides output from the child process. Otherwise, it is ``None``.
.. attribute:: Popen.stderr
- If the *stderr* argument is ``PIPE``, this attribute is file object that
- provides error output from the child process. Otherwise, it is ``None``.
+ If the *stderr* argument was :data:`PIPE`, this attribute is a file object
+ that provides error output from the child process. Otherwise, it is
+ ``None``.
.. attribute:: Popen.pid
print("Execution failed:", e, file=sys.stderr)
-Replacing os.spawn\*
-^^^^^^^^^^^^^^^^^^^^
+Replacing the os.spawn family
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
P_NOWAIT example::
Popen(["/bin/mycmd", "myarg"], env={"PATH": "/usr/bin"})
-Replacing os.popen\*
-^^^^^^^^^^^^^^^^^^^^
+Replacing os.popen
+^^^^^^^^^^^^^^^^^^
::
pipe = os.popen(cmd, 'w', bufsize)
==>
pipe = Popen(cmd, shell=True, bufsize=bufsize, stdin=PIPE).stdin
-
Basic customization
-------------------
-
.. method:: object.__new__(cls[, ...])
+ .. index:: pair: subclassing; immutable types
+
Called to create a new instance of class *cls*. :meth:`__new__` is a static
method (special-cased so you need not declare it as such) that takes the class
of which an instance was requested as its first argument. The remaining
True
In addition to bypassing any instance attributes in the interest of
-correctness, implicit special method lookup may also bypass the
+correctness, implicit special method lookup generally also bypasses the
:meth:`__getattribute__` method even of the object's metaclass::
>>> class Meta(type):
{% extends "!layout.html" %}
{% block rootrellink %}
-<li><img src="{{ pathto('_static/py.png', 1) }}" alt="" style="vertical-align: middle; margin-top: -1px"/></li><li><a href="{{ pathto('index') }}">{{ shorttitle }}</a>{{ reldelim1 }}</li>
+ <li><img src="{{ pathto('_static/py.png', 1) }}" alt=""
+ style="vertical-align: middle; margin-top: -1px"/></li>
+ <li><a href="{{ pathto('index') }}">{{ shorttitle }}</a>{{ reldelim1 }}</li>
+{% endblock %}
+{% block extrahead %}
+ <link rel="shortcut icon" type="image/png" href="{{ pathto('_static/py.png', 1) }}" />
+{{ super() }}
{% endblock %}
range(-10, -100, -30)
-10, -40, -70
-To iterate over the indices of a sequence, combine :func:`range` and :func:`len`
-as follows::
+To iterate over the indices of a sequence, you can combine :func:`range` and
+:func:`len` as follows::
>>> a = ['Mary', 'had', 'a', 'little', 'lamb']
>>> for i in range(len(a)):
3 little
4 lamb
+In most such cases, however, it is convenient to use the :func:`enumerate`
+function, see :ref:`tut-loopidioms`.
+
A strange thing happens if you just print a range::
>>> print(range(10))
Later we will see more functions that return iterables and take iterables as argument.
+
.. _tut-break:
:keyword:`break` and :keyword:`continue` Statements, and :keyword:`else` Clauses on Loops
import string, re
-__all__ = ['TextWrapper', 'wrap', 'fill']
+__all__ = ['TextWrapper', 'wrap', 'fill', 'dedent']
# Hardcode the recognized whitespace characters to the US-ASCII
# whitespace characters. The main reason for doing this is that in
projects / python / commitdiff