Polyhedron.delete -> _delete

[nathanncohen]

From the doc of Polyhedron.delete (which is a immutable/hashable object):

        Delete this polyhedron.

        This speeds up creation of new polyhedra by reusing
        objects. After recycling a polyhedron object, it is not in a
        consistent state any more and neither the polyhedron nor its
        H/V-representation objects may be used any more.

This really shouldn't be exposed at user level:

sage: p = polytopes.cube()
sage: p.delete()
sage: p
/home/ncohen/.Sage/local/lib/python2.7/site-packages/sage/repl/rich_output/display_manager.py:570: RichReprWarning: Exception in _rich_repr_ while displaying object: object of type 'NoneType' has no len()
  RichReprWarning,
<repr(<sage.geometry.polyhedron.backend_ppl.Polyhedra_ZZ_ppl_with_category.element_class at 0x7f1f17c92c30>) failed: TypeError: object of type 'NoneType' has no len()>

CC: @videlec @dimpase @vbraun

Component: geometry

Author: Nathann Cohen

Branch/Commit: c502543

Reviewer: Dima Pasechnik

Issue created by migration from https://trac.sagemath.org/ticket/18814

[nathanncohen]

Branch: public/18814

[nathanncohen]

Commit: 2dd3eb6

[nathanncohen]

New commits:

2dd3eb6

trac #18814: Polyhedron.delete -> _delete

[vbraun]

comment:2

Renaming it doesn't really address your point that it is immutable.

I also thought we are all consenting adults.

I agree that a better implementation should be provided, but just renaming it is not doing anything.

[nathanncohen]

comment:3

What exactly do you want?

[sagetrac-git]

Changed commit from 2dd3eb6 to c502543

[sagetrac-git]

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

5bcf79f	Merge branch 'public/18814' into 6.9.b4
c502543	trac #18814 fixing doctest continuation

[dimpase]

comment:5

LGTM

[dimpase]

Reviewer: Dima Pasechnik

[vbraun]

Changed branch from public/18814 to c502543