#1286: allow using fileinput.FileInput as context manager.
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@ -24,7 +24,7 @@ as the first argument to :func:`.input`. A single file name is also allowed.
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All files are opened in text mode by default, but you can override this by
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specifying the *mode* parameter in the call to :func:`.input` or
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:class:`FileInput()`. If an I/O error occurs during opening or reading a file,
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:class:`FileInput`. If an I/O error occurs during opening or reading a file,
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:exc:`IOError` is raised.
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If ``sys.stdin`` is used more than once, the second and further use will return
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@ -54,6 +54,16 @@ The following function is the primary interface of this module:
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during iteration. The parameters to this function will be passed along to the
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constructor of the :class:`FileInput` class.
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The :class:`FileInput` instance can be used as a context manager in the
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:keyword:`with` statement. In this example, *input* is closed after the
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:keyword:`with` statement is exited, even if an exception occurs::
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with fileinput.input(files=('spam.txt', 'eggs.txt')) as input:
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process(input)
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.. versionchanged:: 3.2
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Can be used as a context manager.
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The following functions use the global state created by :func:`fileinput.input`;
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if there is no active state, :exc:`RuntimeError` is raised.
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@ -132,13 +142,23 @@ available for subclassing as well:
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*filename* and *mode*, and returns an accordingly opened file-like object. You
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cannot use *inplace* and *openhook* together.
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A :class:`FileInput` instance can be used as a context manager in the
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:keyword:`with` statement. In this example, *input* is closed after the
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:keyword:`with` statement is exited, even if an exception occurs::
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**Optional in-place filtering:** if the keyword argument ``inplace=1`` is passed
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to :func:`fileinput.input` or to the :class:`FileInput` constructor, the file is
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moved to a backup file and standard output is directed to the input file (if a
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file of the same name as the backup file already exists, it will be replaced
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silently). This makes it possible to write a filter that rewrites its input
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file in place. If the *backup* parameter is given (typically as
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with FileInput(files=('spam.txt', 'eggs.txt')) as input:
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process(input)
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.. versionchanged:: 3.2
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Can be used as a context manager.
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**Optional in-place filtering:** if the keyword argument ``inplace=True`` is
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passed to :func:`fileinput.input` or to the :class:`FileInput` constructor, the
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file is moved to a backup file and standard output is directed to the input file
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(if a file of the same name as the backup file already exists, it will be
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replaced silently). This makes it possible to write a filter that rewrites its
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input file in place. If the *backup* parameter is given (typically as
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``backup='.<some extension>'``), it specifies the extension for the backup file,
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and the backup file remains around; by default, the extension is ``'.bak'`` and
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it is deleted when the output file is closed. In-place filtering is disabled
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@ -238,6 +238,12 @@ class FileInput:
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self.nextfile()
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self._files = ()
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def __enter__(self):
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return self
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def __exit__(self, type, value, traceback):
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self.close()
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def __iter__(self):
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return self
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@ -231,6 +231,30 @@ class FileInputTests(unittest.TestCase):
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## finally:
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## remove_tempfiles(t1)
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def test_context_manager(self):
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try:
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t1 = writeTmp(1, ["A\nB\nC"])
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t2 = writeTmp(2, ["D\nE\nF"])
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with FileInput(files=(t1, t2)) as fi:
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lines = list(fi)
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self.assertEqual(lines, ["A\n", "B\n", "C", "D\n", "E\n", "F"])
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self.assertEqual(fi.filelineno(), 3)
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self.assertEqual(fi.lineno(), 6)
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self.assertEqual(fi._files, ())
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finally:
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remove_tempfiles(t1, t2)
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def test_close_on_exception(self):
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try:
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t1 = writeTmp(1, [""])
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with FileInput(files=t1) as fi:
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raise IOError
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except IOError:
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self.assertEqual(fi._files, ())
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finally:
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remove_tempfiles(t1)
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def test_main():
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run_unittest(BufferSizesTests, FileInputTests)
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