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Make BZ2File's fileobj support easier to use. 

The fileobj argument was added during the 3.3 development cycle, so this change
does not break backward compatibility with 3.2.
This commit is contained in:
Nadeem Vawda 2012-06-04 23:31:20 +02:00
parent 68721019ef
commit aebcdba829
5 changed files with 49 additions and 31 deletions
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16
Doc/library/bz2.rst
View File

@ -26,17 +26,18 @@ All of the classes in this module may safely be accessed from multiple threads.
(De)compression of files
------------------------
.. class:: BZ2File(filename=None, mode='r', buffering=None, compresslevel=9, \*, fileobj=None)
.. class:: BZ2File(filename, mode='r', buffering=None, compresslevel=9)
Open a bzip2-compressed file.
The :class:`BZ2File` can wrap an existing :term:`file object` (given by
*fileobj*), or operate directly on a named file (named by *filename*).
Exactly one of these two parameters should be provided.
If *filename* is a :class:`str` or :class:`bytes` object, open the named file
directly. Otherwise, *filename* should be a :term:`file object`, which will
be used to read or write the compressed data.
The *mode* argument can be either ``'r'`` for reading (default), ``'w'`` for
overwriting, or ``'a'`` for appending. If *fileobj* is provided, a mode of
``'w'`` does not truncate the file, and is instead equivalent to ``'a'``.
overwriting, or ``'a'`` for appending. If *filename* is a file object (rather
than an actual file name), a mode of ``'w'`` does not truncate the file, and
is instead equivalent to ``'a'``.
The *buffering* argument is ignored. Its use is deprecated.
@ -69,7 +70,8 @@ All of the classes in this module may safely be accessed from multiple threads.
:meth:`read1` and :meth:`readinto` methods were added.
.. versionchanged:: 3.3
The *fileobj* argument to the constructor was added.
Support was added for *filename* being a :term:`file object` instead of an
actual filename.
.. versionchanged:: 3.3
The ``'a'`` (append) mode was added, along with support for reading

17
Lib/bz2.py
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@ -39,13 +39,12 @@ class BZ2File(io.BufferedIOBase):
returned as bytes, and data to be written should be given as bytes.
"""
def __init__(self, filename=None, mode="r", buffering=None,
compresslevel=9, *, fileobj=None):
def __init__(self, filename, mode="r", buffering=None, compresslevel=9):
"""Open a bzip2-compressed file.
If filename is given, open the named file. Otherwise, operate on
the file object given by fileobj. Exactly one of these two
parameters should be provided.
If filename is a str or bytes object, is gives the name of the file to
be opened. Otherwise, it should be a file object, which will be used to
read or write the compressed data.
mode can be 'r' for reading (default), 'w' for (over)writing, or
'a' for appending.
@ -91,15 +90,15 @@ class BZ2File(io.BufferedIOBase):
else:
raise ValueError("Invalid mode: {!r}".format(mode))
if filename is not None and fileobj is None:
if isinstance(filename, (str, bytes)):
self._fp = open(filename, mode)
self._closefp = True
self._mode = mode_code
elif fileobj is not None and filename is None:
self._fp = fileobj
elif hasattr(filename, "read") or hasattr(filename, "write"):
self._fp = filename
self._mode = mode_code
else:
raise ValueError("Must give exactly one of filename and fileobj")
raise TypeError("filename must be a str or bytes object, or a file")
def close(self):
"""Flush and close the file.

4
Lib/tarfile.py
View File

@ -1657,8 +1657,8 @@ class TarFile(object):
except ImportError:
raise CompressionError("bz2 module is not available")
fileobj = bz2.BZ2File(filename=name if fileobj is None else None,
mode=mode, fileobj=fileobj, compresslevel=compresslevel)
fileobj = bz2.BZ2File(fileobj or name, mode,
compresslevel=compresslevel)
try:
t = cls.taropen(name, mode, fileobj, **kwargs)

40
Lib/test/test_bz2.py
View File

@ -81,6 +81,20 @@ class BZ2FileTest(BaseTest):
with open(self.filename, "wb") as f:
f.write(self.DATA * streams)
def testBadArgs(self):
with self.assertRaises(TypeError):
BZ2File(123.456)
with self.assertRaises(ValueError):
BZ2File("/dev/null", "z")
with self.assertRaises(ValueError):
BZ2File("/dev/null", "rx")
with self.assertRaises(ValueError):
BZ2File("/dev/null", "rbt")
with self.assertRaises(ValueError):
BZ2File("/dev/null", compresslevel=0)
with self.assertRaises(ValueError):
BZ2File("/dev/null", compresslevel=10)
def testRead(self):
self.createTempFile()
with BZ2File(self.filename) as bz2f:
@ -348,7 +362,7 @@ class BZ2FileTest(BaseTest):
def testFileno(self):
self.createTempFile()
with open(self.filename, 'rb') as rawf:
bz2f = BZ2File(fileobj=rawf)
bz2f = BZ2File(rawf)
try:
self.assertEqual(bz2f.fileno(), rawf.fileno())
finally:
@ -356,7 +370,7 @@ class BZ2FileTest(BaseTest):
self.assertRaises(ValueError, bz2f.fileno)
def testSeekable(self):
bz2f = BZ2File(fileobj=BytesIO(self.DATA))
bz2f = BZ2File(BytesIO(self.DATA))
try:
self.assertTrue(bz2f.seekable())
bz2f.read()
@ -365,7 +379,7 @@ class BZ2FileTest(BaseTest):
bz2f.close()
self.assertRaises(ValueError, bz2f.seekable)
bz2f = BZ2File(fileobj=BytesIO(), mode="w")
bz2f = BZ2File(BytesIO(), mode="w")
try:
self.assertFalse(bz2f.seekable())
finally:
@ -374,7 +388,7 @@ class BZ2FileTest(BaseTest):
src = BytesIO(self.DATA)
src.seekable = lambda: False
bz2f = BZ2File(fileobj=src)
bz2f = BZ2File(src)
try:
self.assertFalse(bz2f.seekable())
finally:
@ -382,7 +396,7 @@ class BZ2FileTest(BaseTest):
self.assertRaises(ValueError, bz2f.seekable)
def testReadable(self):
bz2f = BZ2File(fileobj=BytesIO(self.DATA))
bz2f = BZ2File(BytesIO(self.DATA))
try:
self.assertTrue(bz2f.readable())
bz2f.read()
@ -391,7 +405,7 @@ class BZ2FileTest(BaseTest):
bz2f.close()
self.assertRaises(ValueError, bz2f.readable)
bz2f = BZ2File(fileobj=BytesIO(), mode="w")
bz2f = BZ2File(BytesIO(), mode="w")
try:
self.assertFalse(bz2f.readable())
finally:
@ -399,7 +413,7 @@ class BZ2FileTest(BaseTest):
self.assertRaises(ValueError, bz2f.readable)
def testWritable(self):
bz2f = BZ2File(fileobj=BytesIO(self.DATA))
bz2f = BZ2File(BytesIO(self.DATA))
try:
self.assertFalse(bz2f.writable())
bz2f.read()
@ -408,7 +422,7 @@ class BZ2FileTest(BaseTest):
bz2f.close()
self.assertRaises(ValueError, bz2f.writable)
bz2f = BZ2File(fileobj=BytesIO(), mode="w")
bz2f = BZ2File(BytesIO(), mode="w")
try:
self.assertTrue(bz2f.writable())
finally:
@ -512,14 +526,14 @@ class BZ2FileTest(BaseTest):
def testReadBytesIO(self):
with BytesIO(self.DATA) as bio:
with BZ2File(fileobj=bio) as bz2f:
with BZ2File(bio) as bz2f:
self.assertRaises(TypeError, bz2f.read, None)
self.assertEqual(bz2f.read(), self.TEXT)
self.assertFalse(bio.closed)
def testPeekBytesIO(self):
with BytesIO(self.DATA) as bio:
with BZ2File(fileobj=bio) as bz2f:
with BZ2File(bio) as bz2f:
pdata = bz2f.peek()
self.assertNotEqual(len(pdata), 0)
self.assertTrue(self.TEXT.startswith(pdata))
@ -527,7 +541,7 @@ class BZ2FileTest(BaseTest):
def testWriteBytesIO(self):
with BytesIO() as bio:
with BZ2File(fileobj=bio, mode="w") as bz2f:
with BZ2File(bio, "w") as bz2f:
self.assertRaises(TypeError, bz2f.write)
bz2f.write(self.TEXT)
self.assertEqual(self.decompress(bio.getvalue()), self.TEXT)
@ -535,14 +549,14 @@ class BZ2FileTest(BaseTest):
def testSeekForwardBytesIO(self):
with BytesIO(self.DATA) as bio:
with BZ2File(fileobj=bio) as bz2f:
with BZ2File(bio) as bz2f:
self.assertRaises(TypeError, bz2f.seek)
bz2f.seek(150)
self.assertEqual(bz2f.read(), self.TEXT[150:])
def testSeekBackwardsBytesIO(self):
with BytesIO(self.DATA) as bio:
with BZ2File(fileobj=bio) as bz2f:
with BZ2File(bio) as bz2f:
bz2f.read(500)
bz2f.seek(-150, 1)
self.assertEqual(bz2f.read(), self.TEXT[500-150:])

3
Misc/NEWS
View File

@ -15,6 +15,9 @@ Core and Builtins
Library
-------
- BZ2File.__init__() now accepts a file object as its first argument, rather
than requiring a separate "fileobj" argument.
- gzip.open() now accepts file objects as well as filenames.
- Issue #14992: os.makedirs(path, exist_ok=True) would raise an OSError