diff options
Diffstat (limited to 'Doc/library/fileinput.rst')
| -rw-r--r-- | Doc/library/fileinput.rst | 55 |
1 files changed, 30 insertions, 25 deletions
diff --git a/Doc/library/fileinput.rst b/Doc/library/fileinput.rst index 172a643..ac44311 100644 --- a/Doc/library/fileinput.rst +++ b/Doc/library/fileinput.rst @@ -27,7 +27,7 @@ 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 @@ -50,15 +50,24 @@ provided by this module. The following function is the primary interface of this module: -.. function:: input([files[, inplace[, backup[, mode[, openhook]]]]]) +.. function:: input(files=None, inplace=False, backup='', bufsize=0, mode='r', openhook=None) Create an instance of the :class:`FileInput` class. The instance will be used as global state for the functions of this module, and is also returned to use during iteration. The parameters to this function will be passed along to the constructor of the :class:`FileInput` class. - .. versionchanged:: 2.5 - Added the *mode* and *openhook* parameters. + 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 f: + for line in f: + process(line) + + .. 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. @@ -75,8 +84,6 @@ if there is no active state, :exc:`RuntimeError` is raised. Return the integer "file descriptor" for the current file. When no file is opened (before the first line and between files), returns ``-1``. - .. versionadded:: 2.5 - .. function:: lineno() @@ -122,7 +129,7 @@ The class which implements the sequence behavior provided by the module is available for subclassing as well: -.. class:: FileInput([files[, inplace[, backup[, mode[, openhook]]]]]) +.. class:: FileInput(files=None, inplace=False, backup='', bufsize=0, mode='r', openhook=None) Class :class:`FileInput` is the implementation; its methods :meth:`filename`, :meth:`fileno`, :meth:`lineno`, :meth:`filelineno`, :meth:`isfirstline`, @@ -139,15 +146,23 @@ available for subclassing as well: *filename* and *mode*, and returns an accordingly opened file-like object. You cannot use *inplace* and *openhook* together. - .. versionchanged:: 2.5 - Added the *mode* and *openhook* parameters. + 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:: + + 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=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 + +**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 @@ -169,8 +184,6 @@ The two following opening hooks are provided by this module: Usage example: ``fi = fileinput.FileInput(openhook=fileinput.hook_compressed)`` - .. versionadded:: 2.5 - .. function:: hook_encoded(encoding) @@ -179,11 +192,3 @@ The two following opening hooks are provided by this module: Usage example: ``fi = fileinput.FileInput(openhook=fileinput.hook_encoded("iso-8859-1"))`` - - .. note:: - - With this hook, :class:`FileInput` might return Unicode strings depending on the - specified *encoding*. - - .. versionadded:: 2.5 - |