On Saturday, January 31, 2015 at 9:15:33 AM UTC-8, vdelecroix wrote:
>
> I found out where it is. The Interface objects inherits from
> ParentWithBasis and the base is itself...
>
> sage: p = Gp()
> sage: p._base is p
> True
>
Hm, that's a problem. Parent objects are virtually always involved in
cyclic references (e.g., rings will hold references to "zero" and "one"
objects which, being elements, refer back to the ring). So trying to
eliminate circular references will be hard/futile. Does Gp need to inherit
from parent? almost certainly, I guess ...
So we need to make our expect interface wrappers deletable in the presence
of circular references. One solution is to upgrade to Python 3. Another is
to put all the "__del__" code into a separate object that the "parent"
object holds a reference to, but that itself does not refer to the parent.
Then the __del__-equipped object is not involved in a cycle. Since the
standard del tries to call self.quit(), it would require a significant bit
of refactoring.
Plus, ParentWithBase is deprecated. So perhaps we should go for a quick fix
anyway: self._base seems to be the only self-reference, so:
--- a/src/sage/interfaces/interface.py
+++ b/src/sage/interfaces/interface.py
@@ -59,7 +59,7 @@ class Interface(ParentWithBase):
self.__coerce_name = '_' + name.lower() + '_'
self.__seq = -1
self._available_vars = []
- ParentWithBase.__init__(self, self)
+ ParentWithBase.__init__(self, None)
might be an acceptable solution for now. Having "__del__" methods in sage
is always risky, because many structures end up having cycles.
--
You received this message because you are subscribed to the Google Groups
"sage-devel" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to sage-devel+unsubscr...@googlegroups.com.
To post to this group, send email to sage-devel@googlegroups.com.
Visit this group at http://groups.google.com/group/sage-devel.
For more options, visit https://groups.google.com/d/optout.
