id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
10906 lazy import can break unique representation Nicolas M. Thiéry Jason Grout "A fun experiment: edit sage/categories/semigroups, and add the following lines at the beginning:
{{{
from sage.misc.lazy_import import lazy_import
lazy_import('sage.rings.rational_field', 'QQ')
}}}
Then restart sage:
{{{
sage: sage.categories.semigroups.QQ is QQ
False
}}}
This bit me hard, because such a lazy_import indirectly changed the base ring of a matrix to be equal to QQ but not identical, which in turn broke all the linear algebra: I was getting a matrix space over QQ whose elements were generic matrices. " defect closed major sage-duplicate/invalid/wontfix misc duplicate lazy import, unique representation Robert Bradshaw Jeroen Demeyer N/A