Methods __round__, __trunc__, __floor__, __ceil__

[fchapoton]

https://docs.python.org/3/reference/datamodel.html?highlight=__round__#object.__round__

We should define these special methods so that the built-in round and math.trunc, math.floor, math.ceil can operate on Sage numbers.

This can help to eliminate imports of floor and ceil from sage.functions throughout the Sage library, which pulls in all of sage.symbolic.

Related: In the global namespace, we have:

• round = sage.misc.functional.round,
• floor = sage.functions.other.floor,
• ceil = sage.functions.other.ceil,
• trunc - undefined

CC: @jdemeyer @tscrim

Component: python3

Author: Frédéric Chapoton

Branch/Commit: public/ticket/25827 @ 53280c5

Issue created by migration from https://trac.sagemath.org/ticket/25827

[fchapoton]

New commits:

f79a61b

some changes about round

[fchapoton]

Commit: f79a61b

[fchapoton]

Branch: u/chapoton/25827

[fchapoton]

comment:2

Not sure what to do. This is not curing the disease. It seems that python3 builtin "round" is looking for __round__, unlike python2.

[fchapoton]

comment:3

failing doctests

[embray]

comment:5

I've implemented a few __round__ in my python3 branch. I'll see about making a ticket for those.

[fchapoton]

comment:6

@embray, where is your latest python3 branch ? could you please provide a branch for here, with the implemented __round__ ?

[embray]

comment:7

Ok, I'll try to get back to you about that soon.