change '__len__' method of propositional formula to 'length'

[DaveWitteMorris]

#28053 added a __len__ method to propositional formulas, so that len(f) would return the length of the formula. However, it was pointed out in #29738 that only containers should have a len. So the method should be renamed to length.

sage: f = propcalc.formula("a -> b")
sage: f.length()
3

For now, __len__ is being retained as an alias.

Component: symbolics

Keywords: boolean formula, len, length

Author: Dave Morris

Branch/Commit: 59cc054

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/32148

[DaveWitteMorris]

Branch: public/32148

[DaveWitteMorris]

Commit: 551f2cc

[DaveWitteMorris]

New commits:

551f2cc

trac 32148 length of propositional formula

[tscrim]

comment:3

I am fine with everything except deprecating this as a __len__. I think we should take a more incremental approach here and just add the alias, but leave it to #29738 once more concrete decisions have been reached before deprecating this behavior.

[sagetrac-git]

Changed commit from 551f2cc to 59cc054

[sagetrac-git]

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

59cc054

do not deprecate __len__

[DaveWitteMorris]

comment:5

Thanks for looking at this. I'm sure this feature is rarely used, so postponing the deprecation is fine with me.

[tscrim]

comment:6

Thank you.

[tscrim]

Reviewer: Travis Scrimshaw

[DaveWitteMorris]

comment:7

Thanks!

[vbraun]

Changed branch from public/32148 to 59cc054