dump()/dumps() fails for class Polyhedron

[sagetrac-terhorst]

Polyhedra (objects of class Polyhedron) cannot be dumped or saved:

sage: polytopes.dodecahedron(QQ).dumps()
---------------------------------------------------------------------------
PicklingError                             Traceback (most recent call last)

/home/terhorst/<ipython console> in <module>()

/opt/sage/local/lib/python2.6/site-packages/sage/structure/sage_object.so in sage.structure.sage_object.SageObject.dumps (sage/structure/sage_object.c:2108)()

PicklingError: Can't pickle <type 'function'>: attribute lookup __builtin__.function failed

As a workaround, I pickle a hash of the rays, vertices, and lines defining the polyhedron.

CC: @vbraun

Component: geometry

Keywords: polyhedron polyhedra pickle dumps dump

Author: Volker Braun

Reviewer: Andrey Novoseltsev

Merged: sage-4.6.1.alpha0

Issue created by migration from https://trac.sagemath.org/ticket/10024

[novoselt]

Changed author from polyhedron polyhedra pickle dumps dump to none

[novoselt]

Changed keywords from none to polyhedron polyhedra pickle dumps dump

[vbraun]

Attachment: trac_10024_dump_fails_for_Polyhedron.patch.gz

Initial patch

[vbraun]

comment:2

Patch fixes load/dump and adds comparisons, for example, P<=Q means P is a not-necessarily-strict subpolyhedron of Q.

[vbraun]

Author: Volker Braun

[novoselt]

comment:3

1. I think __setstate__ would look better without checks for exclude_keys which is unnecessary.
   1. Equality/"non-equality" tests seem to be not the most efficient ones, although for generic polyhedra it is not obvious what one should do instead.
   2. Chosen definition of ==, i.e. equality as sets of points, fits nicely together with other containment checks, but is inconsistent with the current situation for cones and fans. This bugs me a little bit, but not too much and I still prefer cones to take into account the ray order.

Anyway, all this is more like just thinking aloud, I am satisfied with the patch as is and switching it to positive review! (But feel free to address the first issue if you want ;-))

[novoselt]

Reviewer: Andrey Novoseltsev

[jdemeyer]

Merged: sage-4.6.1.alpha0