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bpo-33487: improve BZ2File Deprecation and documentation. #6785

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Merged
gpshead merged 1 commit into from
Sep 11, 2018
Merged

bpo-33487: improve BZ2File Deprecation and documentation. #6785

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6 changes: 5 additions & 1 deletion Doc/library/bz2.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -81,7 +81,7 @@ All of the classes in this module may safely be accessed from multiple threads.
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.
The *buffering* argument is ignored. Its use is deprecated since Python 3.0.

If *mode* is ``'w'`` or ``'a'``, *compresslevel* can be a number between
``1`` and ``9`` specifying the level of compression: ``1`` produces the
Expand Down Expand Up @@ -109,6 +109,10 @@ All of the classes in this module may safely be accessed from multiple threads.

.. versionadded:: 3.3


.. deprecated:: 3.0
The keyword argument *buffering* was deprecated and is now ignored.

.. versionchanged:: 3.1
Support for the :keyword:`with` statement was added.

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14 changes: 9 additions & 5 deletions Lib/bz2.py
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Expand Up @@ -24,6 +24,8 @@
# Value 2 no longer used
_MODE_WRITE = 3

_sentinel = object()


class BZ2File(_compression.BaseStream):

Expand All @@ -36,7 +38,7 @@ class BZ2File(_compression.BaseStream):
returned as bytes, and data to be written should be given as bytes.
"""

def __init__(self, filename, mode="r", buffering=None, compresslevel=9):
def __init__(self, filename, mode="r", buffering=_sentinel, compresslevel=9):
"""Open a bzip2-compressed file.

If filename is a str, bytes, or PathLike object, it gives the
Expand All @@ -47,7 +49,7 @@ def __init__(self, filename, mode="r", buffering=None, compresslevel=9):
'x' for creating exclusively, or 'a' for appending. These can
equivalently be given as 'rb', 'wb', 'xb', and 'ab'.

buffering is ignored. Its use is deprecated.
buffering is ignored since Python 3.0. Its use is deprecated.

If mode is 'w', 'x' or 'a', compresslevel can be a number between 1
and 9 specifying the level of compression: 1 produces the least
Expand All @@ -63,9 +65,11 @@ def __init__(self, filename, mode="r", buffering=None, compresslevel=9):
self._closefp = False
self._mode = _MODE_CLOSED

if buffering is not None:
warnings.warn("Use of 'buffering' argument is deprecated",
DeprecationWarning)
if buffering is not _sentinel:
warnings.warn("Use of 'buffering' argument is deprecated and ignored"
"since Python 3.0.",
DeprecationWarning,
stacklevel=2)

if not (1 <= compresslevel <= 9):
raise ValueError("compresslevel must be between 1 and 9")
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Documentation/2018-05-13-14-44-30.bpo-33487.iLDzFb.rst
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@@ -0,0 +1,3 @@
BZ2file now emit a DeprecationWarning when buffering=None is passed, the
deprecation message and documentation also now explicitely state it is
deprecated since 3.0.