On Sun, Mar 1, 2009 at 5:11 PM, William Stein <wst...@gmail.com> wrote: > On Sun, Mar 1, 2009 at 12:26 PM, William Stein <wst...@gmail.com> wrote: >> On Fri, Feb 13, 2009 at 2:34 AM, Robert Bradshaw >> <rober...@math.washington.edu> wrote: >>> >>> I have written up extensive documentation on the coercion model at >>> http://wiki.sagemath.org/coercion . If you find coercion baffling, >>> confusing, or unuseful, this is especially for you. I am sure there >>> is lots of room for improvement, as what may be obvious to me can be >>> far from obvious to those less familiar with the system. This is >>> intended to be the guide to using coercion--for deeper implementation >>> details see the docstrings in the coerce.pyx (100% coverage) and >>> related files. >>> >>> Eventually, this should all be moved to the reference manual and/or >>> programing guide, but I figured the wiki was the best place to put it >>> at the moment. Comments welcome. >>> >>> - Robert >> >> I was just looking at this from the context of implementing quaternion >> algebras (again) using this framework. It's actually striking how >> most of the code in Sage does not use the new coercion framework. >> The vast majority of rings and other objects in Sage still use the old >> framework. E.g., there are 88 uses of the deprecated _coerce_impl and >> there are only about 12 uses of the new _populate_coercion_list >> replacement. Because it hasn't got used so much in Sage, maybe the >> new coercion model implementation probably has a lot of kinks to be >> worked out, and people will likely run into these when trying to >> implement classes that use it. >> >> For example, I tried to get pickling of quaternion algebras to work -- >> and it won't if I use >> >> self._populate_coercion_lists_(coerce_list=[base_ring]) >> >> in my code. It gave "weird errors" unless I comment it out, so I >> checked around Sage (e.g., in free modules) for any other uses of this >> pretty natural obvious use of populate_coercion_list in any deployed >> code. There are 2 or 3 instances in all Sage of this. Not enough to >> educate me.
Robert -- just a quick followup -- I defined a straightforward __reduce__ method and suddenly pickling just worked fine for my new QuaternionAlgebras class. -- William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
