There are actually two issues here which I am currently working on a patch for. One, code generation for classes is based on order of imported modules, not on the base class dependencies between the classes. I ended up sorting them by dependencies and this fixed that issue. There is a second issue I am still working on which is that cython does not always generate correct module initialization code in the circular dependence case. This results in the attribute error that is sometimes observed. It seems like this arises from circular imports in the python code and not in the symbolic code. I think that it arises because creating classes involves __init__ and thus we end up with circular imports in python. I feel liike we ought to be able to detect this somehow though and prevent it. However, the problem seems to me to be that currently cython source files are compiled and linked into separate objects. It may be necessary to implement a link time solution to the issue by linking multiple cython files together and then not load the modules that are linked together, but instead leave the pointers to be relocated by the linker.
On 2/24/08, David Harvey <[EMAIL PROTECTED]> wrote: > > Hi, > > In Sage, if I try to add > > from sage.rings.integer cimport Integer > > at the top of sage/misc/misc_c.pyx, everything compiles fine, but > then I get some weird import error when I start up sage. > > (I'm sorry, I don't know enough about cython to reproduce this in a > standalone cython program, I only know how to make it happen in sage.) > > It looks like a "circular cimport problem". I found this post by Greg > Ewing which seems relevant, but it's a bit old now, and I don't quite > understand what he's saying: > > http://osdir.com/ml/python.pyrex/2006-06/msg00020.html > > Is there any way to successfully cimport Integer into that module? Or > do I need to just put the code that references Integer in some other > random place which is guaranteed to get loaded after > sage.rings.integer? (This would be a bit annoying....) > > I don't quite understand why circular cimports should exist, since I > thought these kinds of things got resolved at compile time. > > david > > _______________________________________________ > Cython-dev mailing list > Cython-dev@codespeak.net > http://codespeak.net/mailman/listinfo/cython-dev >
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