On Monday, April 23, 2018 at 8:41:30 PM UTC-7, Martin R wrote:
>
> Hi there,
>
> Since 8.2.rc0 (the update to cython 0.28.1) I'm having trouble using
> pyximport. Here is a minimal non working example:
>
> ######## minimal.py ############
> import pyximport; pyximport.install();
> from minimal_pyx import minimal_fun
> ######## end minimal.py ############
>
> ######## minimal_pyx.pyx ############
> from sage.misc.cachefunc import cached_method
>
> def minimal_fun():
> print("hi")
> ######## end minimal_pyx.pyx ############
>
> Running this with "sage minimal.py" fails as reproduced below.
>
> It seems that I should somehow set the compile_time_env variable
> 'PY_VERSION_HEX', and set it to sys.hexversion. I don't know how to do
> that (especially not when using pyximport), and I'm puzzled because I would
> have thought that dict_del_by_value.pyx is already compiled...
>
> Thanks for any hints or workarounds!
>
> Martin
>
The problem seems to be that pyximport gets its hooks a little too deeply
into the import system (see the documentation: they warn that pyximport
only works in simple cases).
In this case, it seems that "import sage.misc.cachefunc" tries to do a
little too much when the pyximport hook is active. A workaround is to make
sure it's imported before the hook is activated, i.e.,
import sage.misc.cachefunc
import pyximport; pyximport.install();
from minimal_pyx import minimal_fun
seems to do the trick.
To cover all cases, perhaps try "import sage.all" before activating the
hook. That should get you into a state that's comparable to what you have
at the sage prompt. Quoting from the cython manual:
This allows you to automatically run Cython on every .pyx that Python is
> trying to import. You should use this for simple Cython builds only where
> no extra C libraries and no special building setup is needed.
>
ostensibly, sage doesn't qualify; so I think it's not a bug that you need a
workaround.
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