On Tue, Jan 8, 2013 at 8:37 AM, R. David Murray
Eli Bendersky
wrote: Everything works fine. However, if I add import_fresh_module for the C module:
from test.support import import_fresh_module import pickle C = import_fresh_module('xml.etree.ElementTree', fresh=['_elementtree']) P = import_fresh_module('xml.etree.ElementTree', blocked=['_elementtree'])
sys.modules still contains the C version at this point, so:
sys.modules['xml.etree.ElementTree'] = P
tb = P.TreeBuilder() print(pickle.dumps(tb))
This interaction only seems to happen with pickle. What's going on here? Can we somehow improve import_fresh_module to avoid this? Perhaps actually deleting previously imported modules with some special keyword flag?
pickle always looks up sys.modules['xml.etree.ElementTree']. Perhaps we could improve something, but this requirement is rather special;
On Tue, 08 Jan 2013 17:05:50 +0100, Stefan Krah
wrote: personally I'm okay with switching sys.modules explicitly in the tests, because that reminds me of what pickle does.
Handling this case is why having a context-manager form of import_fresh_module was suggested earlier in this meta-thread. At least, I think that would solve it, I haven't tried it :)
Would you mind extracting just this idea into this discussion so we can focus on it here? I personally don't see how making import_fresh_module a context manager will solve things, unless you add some extra functionality to it? AFAIU it doesn't remove modules from sys.modules *before* importing, at this point. Eli