Meta-ticket for Python 3.6+ preparation (sage library) - stage 1

[wluebbe]

For progress on making all doctests pass, see #26212

This ticket tracks a number of other tickets that relate to various tasks to prepare Sage code for Python 3.

The following table lists those fixers from 2to3 that are applicable for stage 1.

//stage 1// includes those 2to3 fixers that produce code which can run on Python 2.7 (possibly using some from __future__ import ... or from future_builtins import ...). The code will usually not run on Python 3.

//stage 2// has those 2to3 fixers (and possibly others) that produce code which can run on Python 3 (more precisely Python 3.3+). The code can run on Python 2 only with the support of imported "compatibility" libraries. Stage 2 is now meta-ticket #16052.

After completion of stage 1 and 2 Sage should have a single, common code base for Python 2.7 and Python 3.3+.

No.	2to3 fixer	see ticket	Comment
1	apply	none	Nothing to change
3	buffer	none	Nothing to change
4	callable	none	No need to change (reintroduced in Python 3.2)
6	except	#15982	about 98 py&pyx modules
9	exitfunc	none	Nothing to change
10	filter	#16067	about 53 modules
11	funcattrs	#15983	about 17 py&pyx modules; since Py2.6 compatible fcts available
12	future	none	do NOT run, as we want to keep from `future` import xxx
13	getcwdu	none	Nothing to change
14	has_key	#15784	Nothing to change, since already done
15	idioms	#15984	about 145 py&pyx modules; details see ticket
16	import	#15985, #22808	about 568 py modules; with from `future` import absolute_import
18	imports2	none	Nothing to change
19	input	none	Nothing to change
20	intern	none	Nothing to change
21	isinstance	none	Nothing to change
27	methodattrs	#15986	7 py&pyx modules; since Py2.6 compatible fcts available
28	ne	#15734	Done
29a	next	#16075	about 84 modules
32	operator	none	Nothing to change
33	paren	#15988	2 py modules
34	print	#15989	about 204 py modules and many doctests; with from `future` import print_function
35	raise	#15990	about 505 py modules
37	reduce	#16078	about 24 modules
38	renames	#15991	18 py&pyx modules
39	repr	#15992	4 py modules
40	set_literal	none	do NOT run, as it is mere style change
41	standard_error	none	Nothing to change
42	sys_exc	none	Nothing to change
43	throw	none	Nothing to change
44	tuple_params	#15993, #20554
45	types	#15994	5 py modules
48	ws_comma	none	do NOT run; about 13,049 changes; just to enhance readability and PEP8 compliance
50	xreadlines	none	Nothing to change

The following changes do not relate to 2to3:

61	division	#18622, #18578, #15995, #19535, #19536, #19842	up to 411 py modules; with from `future` import division
62	cmp parameter	#16536	a few modules affected
63	rich comparison	#16537	many modules affected

• Note 1: The No. in the above table is an enumeration of the fixers of lib2to3/fixes/*.
• Note 2: No. starting with denote fixers not included in lib2to3/fixes/*.

Component: python3

Issue created by migration from https://trac.sagemath.org/ticket/15980

[ohanar]

comment:4

Hi Wilfried,

There is currently a meta-ticket pertaining to supporting Python 3.3 for the Sage distribution, which includes making various changes to the build system and upgrading various dependencies (see #15530). I've added this meta-ticket to that meta-ticket and changed the summary of this one to better reflect that it is specifically referring to the sage library.

I'm a little confused on your distinction between stage 1 and stage 2. What exactly are things that go into stage 2 but not into stage 1?

I don't see anywhere in this list issues with renamed/reorganized libraries like urllib or StringIO, maybe this is part of the compatibility library that you mention as part of stage 2? Also, probably the biggest issue with Python 3 support is the requirement for rich comparison, which again wasn't mentioned in here.

[wluebbe]

comment:5

Hi Andrew,

Thanks for linking the ticket:15530 and improving the ticket's title.

As for stage 2 I guess I should soon open the respective meta-ticket.

Some reasons for assigning tasks to stage 2:

• The code can run on Python 2 only with the support of imported "compatibility" libraries. [copied from description]
  Maybe we have to check the licenses of the used compatibility libraries.
• The tasks are usually more complicated. The approach may not be obvious or uncontroversial.
• To make progress we need a Python 3.3 test environment for them (can ticket:15530 help?).

And yes, the issues to mention belong to stage 2.

Hopefully the tasks assigned to stage 1 turn out (relatively) easy :-)

[wluebbe]

comment:8

Was changed to "needs review" to allow "needs work".

[wluebbe]

comment:12

Changed No. 10 (ticket:16067) and No. 37 (ticket:16078) from stage 2 to stage 1.

Corrected the fixer name in No. 50 to "xreadlines".

[mkoeppe]

comment:30

Can this be closed?

[fchapoton]

comment:31

ok, let us close this one too.