Python 3 preparation: Change some code to use more modern Python idioms

[wluebbe]

This fixer changes code like type(x) == T) and while 1: and it introduces the sorted() function where appropriate.

These changes are optional, but they improve style and may provide a small performance gain.

Changes according to lib2to3/fixes/fix_idioms.py:

* Change some type comparisons to isinstance() calls:
    type(x) == T -> isinstance(x, T)
    type(x) is T -> isinstance(x, T)
    type(x) != T -> not isinstance(x, T)
    type(x) is not T -> not isinstance(x, T)

* Change "while 1:" into "while True:".

* Change both
    v = list(EXPR)
    v.sort()
    foo(v)

and the more general
    v = EXPR
    v.sort()
    foo(v)

into
    v = sorted(EXPR)
    foo(v)

Component: distribution

Author: Wilfried Luebbe

Branch/Commit: 6964533

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/15984

[wluebbe]

Branch: u/wluebbe/ticket/15984

[wluebbe]

comment:1

• At first I applied the 2to3 tool (idioms) -> first commit
• Fixing the doctests failures of the first commit -> second commit. All tests passed.
• Changed while 1: into while True: for cython modules -> third commit.

---

New commits:

86de429	changes made by 2to3 tool (idioms), many changes
1f05981	reverted changes to 4 modules done by 2to3 tool
85f7d5e	change "while 1:" into "while True:" for .pyx modules

[wluebbe]

Commit: 85f7d5e

[sagetrac-git]

Changed commit from 85f7d5e to 6964533

[sagetrac-git]

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

617b158	changes made by 2to3 tool (idioms), many changes
85ef438	reverted changes to 4 modules done by 2to3 tool
6964533	change "while 1:" into "while True:" for .pyx modules

[wluebbe]

comment:3

Rebased on 6.2.beta6 and resolved merge conflicts.

[wluebbe]

comment:4

And the test report:

All tests passed!
----------------------------------------------------------------------
Total time for all tests: 3214.7 seconds

[tscrim]

comment:5

I think it would also be good to change x == None to x is None while we're at it.

[wluebbe]

comment:6

There are 151 modules (py and pyx combined) which have at least one of == None or != None.

The change makes sense as (by far) most modules use is None or is not None.

But as this change is already pretty large I would prefer to see this change in a separate ticket/branch.

[tscrim]

comment:7

I think it fits well with this ticket (plus how many of those modules overlap with this one?). Also one large sweeping change is the same to me as two large sweeping changes (especially with different commits), but with the added benefit of an only one time potential rebase. If you still disagree and want it in a separate ticket, then you can set this to positive review.

[wluebbe]

Reviewer: Travis Scrimshaw

[wluebbe]

comment:8

I generated 151 patched py and pyx files. 3 pyx files gave doctest failures. And I got merge conflicts with this branch.

Therefor I set this ticket to "positive review" (as suggested above).

I will open a separate ticket for == None and generate fresh patches when this ticket is merged in a beta or release.

[wluebbe]

Author: Wilfried Luebbe

[vbraun]

Changed branch from u/wluebbe/ticket/15984 to 6964533