cPickle documentation incomplete

[gvanrossum]

BPO	616013
Nosy	@freddrake, @birkenfeld, @abalkin, @avassalotti, @benjaminp

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

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GitHub fields:

assignee = None
closed_at = <Date 2013-03-28.10:46:07.954>
created_at = <Date 2002-09-29.01:21:02.000>
labels = ['type-feature', 'docs']
title = 'cPickle documentation incomplete'
updated_at = <Date 2013-03-28.10:46:07.953>
user = 'https://github.com/gvanrossum'

bugs.python.org fields:

activity = <Date 2013-03-28.10:46:07.953>
actor = 'georg.brandl'
assignee = 'docs@python'
closed = True
closed_date = <Date 2013-03-28.10:46:07.954>
closer = 'georg.brandl'
components = ['Documentation']
creation = <Date 2002-09-29.01:21:02.000>
creator = 'gvanrossum'
dependencies = []
files = []
hgrepos = []
issue_num = 616013
keywords = []
message_count = 8.0
messages = ['12536', '12537', '69613', '69614', '70144', '70751', '110349', '185431']
nosy_count = 6.0
nosy_names = ['fdrake', 'georg.brandl', 'belopolsky', 'alexandre.vassalotti', 'benjamin.peterson', 'docs@python']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = 'needs patch'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue616013'
versions = ['Python 2.7']

[gvanrossum]

Many of the differences between the cPickle module and
the pickle module appear undocumented, despite a claim
in the cPickle module that the pickle docs explain the
differences.

For example, I just found that cPickle.Pickler() can be
called without a file argument, which makes it use an
internal list to store the pickled data; and that in
that case it has a method getvalue() that returns the
contents of that list as a string; and that its dump()
method takes a second argument which, if true, calls
the getvalue() method. Who knows what else it supports.

Someone should go over the cPickle source and compare
the API *carefully* with the documented pickle API.

[freddrake]

Logged In: YES
user_id=3066

Unassigning myself; clearly, I've not had time for this.

[avassalotti]

Is this still desired? If so, I have fairly long list of differences
that I could document. Or maybe, I could backport the _pickle module to
Python 2.6, which doesn't have as many differences.

[benjaminp]

+1 to backporting _pickle as cPickle. Do bring it up on python-dev.

[birkenfeld]

No need for gratuitous breakage of cPickle in Python 2.6.

Alexandre, if you can add the list of changes to the documentation, that
would be great.

[gvanrossum]

2.6 should keep the original cPickle, warts and all, for backwards
compatibility. I'd be okay though with also having _pickle there --
just don't call in cPickle (and don't import it from pickle.py either).

[abalkin]

I've just closed bpo-8738 as invalid and surely a document explaining the differences between cPickle and _pickle would save me a lot of effort. It will also help anyone porting from 2.x to 3.x.

Alexandre, do you have any notes that you can share?

[birkenfeld]

Three years later, I don't think anyone is interested in documenting the outdated cPickle.