add nice print method for Sha(Elliptic curve)

[williamstein]

Printing of Sha is ugly:

sage: E = EllipticCurve('37a')
sage: Sha = E.sha(); Sha
<class 'sage.schemes.elliptic_curves.sha.Sha'>

Component: number theory

Issue created by migration from https://trac.sagemath.org/ticket/1847

[aghitza]

comment:2

Looks good.

[sagetrac-mabshoff]

comment:3

This patch causes the following doctest failure:

mabshoff@geom:/scratch/mabshoff/sage-3.3.alpha3$ ./sage -t  devel/sage/sage/schemes/elliptic_curves/ell_rational_field.py
sage -t  "devel/sage/sage/schemes/elliptic_curves/ell_rational_field.py"
**********************************************************************
File "/scratch/mabshoff/sage-3.3.alpha3/devel/sage/sage/schemes/elliptic_curves/ell_rational_field.py", line 3639:
    sage: S
Expected:
    <class 'sage.schemes.elliptic_curves.sha_tate.Sha'>
Got:
    Shafarevich-Tate group for the Elliptic Curve defined by y^2 + y = x^3 - x over Rational Field
**********************************************************************

I guess the obvious fix is to change the doctest.

Cheers,

Michael

[rlmill]

comment:4

Attachment: trac-1847.patch.gz

Patch updated.

[sagetrac-mabshoff]

comment:5

Merged in Sage 3.3.alpha3