I think there is definitely a bug in the __init__ method of the Expression class. Probably it has not been tracked down because this method is quasi never used in the new version of symbolics. However, it raises problems when one wants to derive a suclass from Expression.
The bug is described in details here for the 4.0.1 version. It is still present in the 4.0.2 : http://groups.google.com/group/sage-support/browse_thread/thread/d50dc3bc2bdbeab0/34798c0585fc034f?lnk=gst&q=nicolas#34798c0585fc034f Burcin provided a simple solution that works wonderfully, in the same thread. Should we issue a ticket for this to be included in the future versions ? Thanks to all Nicolas --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
