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#1286: allow using fileinput.FileInput as context manager.

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Georg Brandl 2010-07-31 20:08:15 +00:00
parent e42a59daec
commit 6cb7b6593e
4 changed files with 59 additions and 7 deletions
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34
Doc/library/fileinput.rst
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@ -24,7 +24,7 @@ as the first argument to :func:`.input`. A single file name is also allowed.
All files are opened in text mode by default, but you can override this by
specifying the *mode* parameter in the call to :func:`.input` or
:class:`FileInput()`. If an I/O error occurs during opening or reading a file,
:class:`FileInput`. If an I/O error occurs during opening or reading a file,
:exc:`IOError` is raised.
If ``sys.stdin`` is used more than once, the second and further use will return
@ -54,6 +54,16 @@ The following function is the primary interface of this module:
during iteration. The parameters to this function will be passed along to the
constructor of the :class:`FileInput` class.
The :class:`FileInput` instance can be used as a context manager in the
:keyword:`with` statement. In this example, *input* is closed after the
:keyword:`with` statement is exited, even if an exception occurs::
with fileinput.input(files=('spam.txt', 'eggs.txt')) as input:
process(input)
.. versionchanged:: 3.2
Can be used as a context manager.
The following functions use the global state created by :func:`fileinput.input`;
if there is no active state, :exc:`RuntimeError` is raised.
@ -132,13 +142,23 @@ available for subclassing as well:
*filename* and *mode*, and returns an accordingly opened file-like object. You
cannot use *inplace* and *openhook* together.
A :class:`FileInput` instance can be used as a context manager in the
:keyword:`with` statement. In this example, *input* is closed after the
:keyword:`with` statement is exited, even if an exception occurs::
**Optional in-place filtering:** if the keyword argument ``inplace=1`` is passed
to :func:`fileinput.input` or to the :class:`FileInput` constructor, the file is
moved to a backup file and standard output is directed to the input file (if a
file of the same name as the backup file already exists, it will be replaced
silently). This makes it possible to write a filter that rewrites its input
file in place. If the *backup* parameter is given (typically as
with FileInput(files=('spam.txt', 'eggs.txt')) as input:
process(input)
.. versionchanged:: 3.2
Can be used as a context manager.
**Optional in-place filtering:** if the keyword argument ``inplace=True`` is
passed to :func:`fileinput.input` or to the :class:`FileInput` constructor, the
file is moved to a backup file and standard output is directed to the input file
(if a file of the same name as the backup file already exists, it will be
replaced silently). This makes it possible to write a filter that rewrites its
input file in place. If the *backup* parameter is given (typically as
``backup='.<some extension>'``), it specifies the extension for the backup file,
and the backup file remains around; by default, the extension is ``'.bak'`` and
it is deleted when the output file is closed. In-place filtering is disabled