get rid of part of itervalues

[fchapoton]

after #29077

There are much more cases, so only half of them is taken care of.

CC: @tscrim @jm58660

Component: refactoring

Author: Frédéric Chapoton

Branch/Commit: cbb20e6

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/29103

[fchapoton]

Branch: u/chapoton/29103

[fchapoton]

New commits:

47f6d46	first parameter must be self
7072bce	get rid of some calls to six.itervalues

[fchapoton]

Commit: 7072bce

[sagetrac-git]

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

7cbd2c2

get rid of some call to six.itervalues

[sagetrac-git]

Changed commit from 7072bce to 7cbd2c2

[sagetrac-git]

Changed commit from 7cbd2c2 to cbb20e6

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

cbb20e6

fix pyflakes warning

[fchapoton]

comment:4

green bot, please review

[tscrim]

comment:5

I am not sure we should be doing this yet given that 9.1 will still be supporting Python2. Although I believe from the sage-devel discussion, are considering 9.0 the last properly Python2 supported version of Sage. So by that, it would be good to do it now. Although if 9.1 is the last such one, then we should wait a little bit I think.

[fchapoton]

comment:6

I did that carefully in such a way that this remains fully python2-compatible.

[tscrim]

comment:7

Sorry, my response was poorly phrased. I meant the efficiency aspects with entire lists being created and returned in Python2 with these changes. I agree that it is fully Python2-compatible, but there will be a speed/memory difference between the two. Admittedly, this is not a very strong position considering the cases where this would matter are somewhat rare IMO. If you think that we should go ahead with only caring about Python3 at this point in time, then we can set this to a positive review.

[tscrim]

Reviewer: Travis Scrimshaw

[fchapoton]

comment:8

I think that people cannot both ask for speed with python2 and use the latest sage..

Therefore setting to positive

[vbraun]

Changed branch from u/chapoton/29103 to cbb20e6