On Mar 5, 2010, at 12:23 AM, Simon King wrote:
Hi Robert!
On Mar 5, 12:42 am, Robert Bradshaw <rober...@math.washington.edu>
wrote:
[...]
As soon as anything is done with the object, it
does a *real* import, replaces itself in G with the real thing, and
since the reference from G is gone, the LazyImport object would
eventually be garbage collected.
I've actually intended to do this as well, it'd be easy, but I just
haven't had time to do it. Note, however, that this is not
transitive,
so the lazy objects may still be around.
You mean, if you have
sage: imp =
LazyImport(globals(),'QQ','sage.rings.rational_field','MyQQ')
then "imp" would remain lazy even if at some point it injects QQ into
globals()? Sure, this would be difficult to circumvent, but that way
of usage is certainly discouraged.
(This is less of an issue for
the global namespace, but if someone does "from sage.all import foo"
they'll have the lazy version forever.)
Why? If you start with a lazy import of "foo" then foo will be a
LazyImport object, to start with. If you then do "from sage.all import
foo" then the reference "foo" to the LazyImport object is replaced by
a reference to what was just imported; as there is no pointer to the
LazyImport object, garbage collection will work.
What I was referring to is the lack of transitivity. If in sage.all
you have
lazy_import("sage.rings.all", "foo")
than anything that does "from sage.all import foo" before foo is
looked up will have the lazy version, even if sage.all's reference is
updated.
There's some other
improvements that I'd like to make too. You willing to referee a
patch
in this direction? :)
Sure! Where is the ticket?
I'll get a patch up later today (I think all that's missing is some
doctests, but I'll have to see).
- Robert
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