a single make_element function for pickling is hard to maintain

[burcin]

All subclasses of sage.structure.element.Element end up using sage.structure.element.make_element for unpickling. This design is very hard to maintain, especially when trying to keep backward compatibility with older pickles.

Python's pickling protocol via __getstate__() and __setstate__() moves the implementation of pickling/unpickling to the subclasses. [1] Attached patch changes sage.structure.element.Element to use this protocol.

[1] http://www.python.org/doc/2.5/lib/pickle-inst.html

CC: @robertwb @williamstein

Component: algebra

Issue created by migration from https://trac.sagemath.org/ticket/4698

[williamstein]

comment:1

Attachment: trac_4698-pickle.patch.gz

I fully doctested this on sage.math and it worked perfectly.

I read the code and it looks good, and like a nice solution. Bravo.

[sagetrac-mabshoff]

comment:2

Merged in Sage 3.2.2.alpha1