Make deques a full MutableSequence by adding index(), insert(), and copy()

[rhettinger]

BPO	23704
Nosy	@rhettinger, @serhiy-storchaka
Files	deque_insert_index_copy3.diff: First draft -- needs doc update and more tests deque_insert_index_copy4.diff: With docs and test

^{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 = 'https://github.com/rhettinger'
closed_at = <Date 2015-03-21.08:39:04.408>
created_at = <Date 2015-03-19.07:11:27.424>
labels = ['type-feature', 'library']
title = 'Make deques a full MutableSequence by adding index(), insert(), and copy()'
updated_at = <Date 2015-03-21.09:28:50.300>
user = 'https://github.com/rhettinger'

bugs.python.org fields:

activity = <Date 2015-03-21.09:28:50.300>
actor = 'serhiy.storchaka'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2015-03-21.08:39:04.408>
closer = 'rhettinger'
components = ['Library (Lib)']
creation = <Date 2015-03-19.07:11:27.424>
creator = 'rhettinger'
dependencies = []
files = ['38552', '38617']
hgrepos = []
issue_num = 23704
keywords = ['patch']
message_count = 7.0
messages = ['238761', '238765', '238769', '238771', '238776', '238777', '238779']
nosy_count = 3.0
nosy_names = ['rhettinger', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'patch review'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue23704'
versions = ['Python 3.5']

[rhettinger]

Attaching an updated patch with documentation updates and tests.

[serhiy-storchaka]

When appending fails, the deque is left in changed state. I would do it in different way. First append new item (can fail), and then make circular shift (never fail). This also should be faster (up to 2 times). Most code can be shared between rotate() and circular shift operation.

[rhettinger]

For now, I prefer to continue using rotate() as a primitive and am saving circular shifts for another day (likely when I start working on slices).

FWIW, the only way for append() to fail is a memory error; in which case, I would ilke to stop doing any work at alll and return a soon as possible, even if it means leaving the deque in a reordered state.

[serhiy-storchaka]

Then the patch LGTM except few nitpicks.

[python-dev]

New changeset 3d33be07c5a2 by Raymond Hettinger in branch 'default':
bpo-23704: Add index(), copy(), and insert() to deques. Register deques as a MutableSequence.
https://hg.python.org/cpython/rev/3d33be07c5a2

[rhettinger]

Thank you for looking it over.

[serhiy-storchaka]

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