bz2.BZ2File doesn't support multiple streams

[55c68216-1b09-421f-b5a4-c375afb3e360]

BPO	1625
Nosy	@loewis, @akuchling, @jcea, @pitrou, @vstinner, @djc, @merwok, @bitdancer
Files	bz2_patch.tar.bz2: issue1625 - bz2 multiple stream patch v1 py3k_bz2.patch: issue1625 - bz2 multiple stream patch v2 py3k_bz2.patch: issue1625 - bz2 multiple stream patch v3 py3k_bz2.patch: issue1625 - bz2 multiple stream patch v4 bz2ms.patch cpython-bz2-streams.patch: Python 3.3 patch to Lib/bz2.py bz2-multiple-stream-support-issue1625.patch: bz2 multiple stream patch for Python 2.7.2

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields: ```python assignee = None closed_at = created_at = labels = ['type-feature', 'library'] title = "bz2.BZ2File doesn't support multiple streams" updated_at = user = 'https://bugs.python.org/therve' ``` bugs.python.org fields: ```python activity = actor = 'python-dev' assignee = 'nirai' closed = True closed_date = closer = 'nadeem.vawda' components = ['Library (Lib)'] creation = creator = 'therve' dependencies = [] files = ['15001', '15014', '15075', '15177', '18939', '22114', '23231'] hgrepos = [] issue_num = 1625 keywords = ['patch', 'needs review'] message_count = 56.0 messages = ['58619', '59897', '60236', '60268', '93323', '93326', '93405', '93407', '93408', '93721', '93841', '94316', '94318', '94321', '94434', '94446', '94499', '101521', '115198', '116964', '118946', '132842', '136689', '136690', '136723', '136753', '136790', '136799', '136889', '137018', '137019', '137074', '137098', '137197', '137228', '137229', '137230', '144404', '144406', '144443', '144445', '144479', '144551', '144552', '144553', '144782', '152144', '152222', '152257', '152327', '152393', '152513', '152551', '152645', '152674', '152681'] nosy_count = 19.0 nosy_names = ['loewis', 'akuchling', 'niemeyer', 'jcea', 'pitrou', 'therve', 'vstinner', 'thomaslee', 'nadeem.vawda', 'djc', 'eric.araujo', 'nirai', 'r.david.murray', 'dbonner', 'ozan.caglayan', 'Kontr-Olli', 'python-dev', 'gkcn', 'Crispin.Wellington'] pr_nums = [] priority = 'normal' resolution = 'fixed' stage = 'resolved' status = 'closed' superseder = None type = 'enhancement' url = 'https://bugs.python.org/issue1625' versions = ['Python 3.3'] ```

[jcea]

Éric, bz2 module in Python is documented as able to manage bz2 files. But that is not true, since it is unable to manage popular bz2 files. That looks like a bug to me. In fact, you can create those files from python, files that python can not unpack later.

Moreover, Python 2.7 is going to live for a long time.

If the refusal of backporting this to 3.2 and 2.7 is firm, I would beg to document this limitation in the 2.7/3.2 docs. It is serious enough.

Please, reconsider backporting this to 2.7, at least.

[merwok]

As the bug/feature judgment is not easy to make, I think python-dev should be asked.

[252699e1-f617-4a8b-9fb0-ae90945f6292]

In fact, you can create those files from python, files that python can not unpack later.

Really? How so? BZ2File only started accepting the "a" mode in 3.3 (thanks to Nir's patch for this issue, actually).

If the refusal of backporting this to 3.2 and 2.7 is firm, I would beg to document this limitation in the 2.7/3.2 docs. It is serious enough.

Of course. I'll add a note to the docs once I've created the bz2file package on PyPI, so we can refer readers to it.

As the bug/feature judgment is not easy to make, I think python-dev should be asked.

Fair enough; I was actually going to suggest consulting the 2.7 release manager, but I suppose getting more opinions on the mailing list makes sense.

[1762cc99-3127-4a62-9baf-30c3d0f51ef7]

New changeset e73d549b7458 by Nadeem Vawda in branch '2.7': Issue bpo-1625: Document BZ2File's lack of support for multi-stream inputs. http://hg.python.org/cpython/rev/e73d549b7458

New changeset 190826ee0450 by Nadeem Vawda in branch '3.2': Issue bpo-1625: Document BZ2File's lack of support for multi-stream inputs. http://hg.python.org/cpython/rev/190826ee0450

[merwok]

Just a thought: maybe the doc note should mention that bz2file is a backport of 3.3’s improved class, so that people know that 1) it’s well-supported code 2) a future Python version will remove the need for the external dependency.

[1762cc99-3127-4a62-9baf-30c3d0f51ef7]

New changeset ad20324229f4 by Nadeem Vawda in branch '2.7': Clarify note in BZ2File docs about lack of multi-stream support (issue bpo-1625). http://hg.python.org/cpython/rev/ad20324229f4

New changeset e4c4595033ad by Nadeem Vawda in branch '3.2': Clarify note in BZ2File docs about lack of multi-stream support (issue bpo-1625). http://hg.python.org/cpython/rev/e4c4595033ad