py3 do not call cmp() in code of real_mpfi

[fchapoton]

as a step to python3

BEWARE: this file will need later a much deeper treatment, because the current behaviour is not possible in python3 (cmp is not the same order as rich comparison)

the current ticket only aims at removing calls to cmp in the code, so that it compiles with cython/python3

CC: @tscrim @jdemeyer @a-andre

Component: python3

Author: Frédéric Chapoton

Branch/Commit: 759ae16

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/22258

[fchapoton]

Commit: 759ae16

[fchapoton]

Branch: u/chapoton/22258

[fchapoton]

New commits:

759ae16

first try of cmp removal in mpfi

[fchapoton]

comment:3

waiting for the bots

[fchapoton]

comment:4

green bot, please review

[tscrim]

comment:5

I'm slightly worried about the richcmp(left.__prec, right.__prec, op) doing more precise comparisons than before and would cause a subtle behavior change. Nor am I not completely convinced the doctests cover all the behavior. I won't have time today to add such tests and verify, but I will try to get to this tomorrow (unless someone who is more familiar with interval comparisons verifies this is okay).

[jdemeyer]

comment:6

Replying to @tscrim:

I'm slightly worried about the richcmp(left.__prec, right.__prec, op) doing more precise comparisons than before and would cause a subtle behavior change.

In this case, the behaviour looks meaningful so it's a change in the good sense.

[fchapoton]

comment:7

ping ?

[tscrim]

Reviewer: Travis Scrimshaw

[tscrim]

comment:8

Okay, then good to go.

[vbraun]

Changed branch from u/chapoton/22258 to 759ae16