py3: import certain things from collections.abc

[slel]

Background (read
Python 3 documentation for the collections module
for more detail):

• Collections Abstract Base Classes
  ("CABCs") moved to the collections.abc module in Python 3.3.

• These "Collections Abstract Base Classes" are: AsyncGenerator,
  AsyncIterable, AsyncIterator, Awaitable, Bytestring,
  Callable, Collection, Container, Coroutine, Generator,
  Hashable, ItemsView, Iterable, Iterator, KeysView,
  Mapping, MappingView, MutableMapping, MutableSequence,
  MutableSet, Reversible, Sequence, Set, Sized, ValuesView.

• For backwards compatibility, CABCs continue to be visible
  in the collections module through Python 3.8; and can be
  imported either from collections or from collections.abc.

• Starting with Python 3.9, CABCs must be imported from collections.abc.

• In Python 2 they could only be imported from 'collections',
  not from 'collections.abc'. So while Sage was keeping
  Py2 and Py3 compatible it made sense to import from collections.

• In Python 3.7 and Python 3.8, importing them from collections
  gives a deprecation warning. This warning was silenced in Sage,
  see py3: last test in tests/cmdline.py #28002.

In this ticket we import the classes from collections.abc.

We do not suppress the silencing of the deprecation warning yet.
See comment:23 and #30768.

CC: @fchapoton @jhpalmieri @slel @videlec @tscrim

Component: python3

Keywords: days101, collections.abc

Author: Samuel Lelièvre

Branch: 4f80136

Reviewer: John Palmieri

Issue created by migration from https://trac.sagemath.org/ticket/28012

[slel]

Branch: u/slelievre/collections.abc

[slel]

Commit: e04fa48

[slel]

New commits:

e04fa48

#28012 import from collections.abc

[slel]

comment:4

Note: to check where such changes were needed I followed advice in a comment at #28002 and did

$ git grep "from collections import"

[slel]

comment:5

More changes are needed, as revealed by

$ git grep "collections\."

I'll push a commit.

[slel]

comment:6

The relevant lines in the output of git grep "collections\." seem to be:

src/sage/arith/misc.py:    if isinstance(ks[0], collections.Iterable):
src/sage/combinat/finite_state_machine.py:                         collections.Iterator):
src/sage/combinat/ranker.py:    from collections.abc import Iterable, Sequence
src/sage/combinat/ranker.py:    tuple (or more generally a :class:`collections.Sequence`), an
src/sage/combinat/ranker.py:    :class:`collections.Iterable`). See :trac:`15919`.
src/sage/combinat/ranker.py:    Lists, tuples, and other :class:`sequences <collections.Sequence>`::
src/sage/combinat/shuffle.py:        assert(isinstance(l1, collections.Iterable) and
src/sage/combinat/shuffle.py:               isinstance(l2, collections.Iterable)
src/sage/combinat/shuffle.py:        assert(all(isinstance(elem, collections.Iterable) for elem in l1))
src/sage/combinat/shuffle.py:        assert(all(isinstance(elem, collections.Iterable) for elem in l2))
src/sage/combinat/shuffle.py:        assert(isinstance(l1, collections.Iterable) and
src/sage/combinat/shuffle.py:               isinstance(l2, collections.Iterable)
src/sage/databases/conway.py:class DictInMapping(collections.Mapping):
src/sage/databases/conway.py:class ConwayPolynomials(collections.Mapping):
src/sage/game_theory/normal_form_game.py:    from collections.abc import MutableMapping
src/sage/geometry/cone.py:                            collections.Hashable,
src/sage/geometry/cone.py:                            collections.Iterable):
src/sage/geometry/cone.py:                                   collections.Container):
src/sage/geometry/fan.py:                            collections.Callable,
src/sage/geometry/fan.py:                            collections.Container):
src/sage/geometry/lattice_polytope.py:class LatticePolytopeClass(SageObject, collections.Hashable):
src/sage/geometry/lattice_polytope.py:                   collections.Hashable):
src/sage/matrix/matrix_integer_sparse.pyx:    from collections.abc import Iterator, Sequence
src/sage/matrix/matrix_modn_sparse.pyx:    from collections.abc import Iterator, Sequence
src/sage/misc/converting_dict.py:            if isinstance(arg, collections.Mapping):
src/sage/modules/with_basis/morphism.py:        if not isinstance(diagonal, collections.Callable):
src/sage/plot/colors.py:class Colormaps(collections.MutableMapping):
src/sage/plot/point.py:    if isinstance(points, collections.Iterator):
src/sage/repl/ipython_kernel/interact.py:    from collections.abc import Iterable, Iterator
src/sage/repl/ipython_kernel/widgets_sagenb.py:    from collections.abc import Iterable, Sequence

[jhpalmieri]

comment:7

Two comments: there may be instances of this in other packages, like matplotlib. Also, it's not just warnings silenced in #28002, but an older silencing in sage/all.py.

[embray]

comment:10

Moving tickets from the Sage 8.8 milestone that have been actively worked on in the last six months to the next release milestone (optimistically).

[embray]

comment:11

Ticket retargeted after milestone closed

[mkoeppe]

comment:12

Moving tickets to milestone sage-9.2 based on a review of last modification date, branch status, and severity.

[mkoeppe]

comment:14

Now that we don't support py2 any more, the try/except approach is not needed any more.

[slel]

Changed keywords from days101 to days101, collections.abc

[slel]

comment:15

Sorry for letting over a year pass by. Here is a new branch. Please review.

The file finite_state_machine.py has import collections
and then collections.defaultdict, collections.OrderedDict,
collections.deque, collections.namedtuple, collections.abc.Iterator.

Would there be an advantage, or a disadvantage, to doing the following instead:

from collections import defaultdict, deque, namedtuple, OrderedDict
from collections.abc import Iterator

and then using defaultdict, OrderedDict, deque, namedtuple, Iterator?

I changed to that style in some other files.

---

New commits:

2187c31

t-28012: Collections Abstract Base Classes

[slel]

Changed commit from e04fa48 to 2187c31

[jhpalmieri]

comment:25

The typical (but not universal) Sage style seems to be "from blah import foo" and then "foo(...)" rather than "import blah" and then "blah.foo(...)". So that's what I would choose, as you suggested.

[sagetrac-git]

Changed commit from 489eccf to 1ee0124

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

1ee0124

t-28012: Collections Abstract Base Classes

[sagetrac-git]

Changed commit from 1ee0124 to 0ce9e40

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

0ce9e40

t-28012: Collections Abstract Base Classes

[slel]

comment:28

Fixed and rebased on 9.2.beta12. Sorry for one more force-push.

[slel]

comment:29

Still needs work. Almost there. Will push shortly.

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

4f80136

t-28012: collections.abc

[sagetrac-git]

Changed commit from 0ce9e40 to 4f80136

[slel]

comment:31

Please review.

[jhpalmieri]

comment:32

Looks good to me.

[jhpalmieri]

Reviewer: John Palmieri

[vbraun]

Changed branch from public/ticket/28012-collections.abc to 4f80136

[slel]

comment:35

Follow-up at #30768 for unsilencing the deprecation warning.

[slel]

Changed commit from 4f80136 to none