[Python-Dev] Status of C compilers for Python on Windows

Sturla Molden sturla.molden at gmail.com
Sat Oct 11 18:58:14 CEST 2014

Steve Dower <Steve.Dower at microsoft.com> wrote:

> Is there some reason the Fortran part can't be separated out into a DLL? 

DLL hell, I assume. Using the Python extension module loader makes it less
of a problem. If we stick with .pyd files where everything is statically
linked we can rely on the Python dev team to make sure that DLL hell does
not bite us. Most of the contributors to projects like NumPy and SciPy are
not computer scientists. So the KISS principle is important, which is why
scientific programmers often use Fortran in the first place. Making sure
DLLs are resolved and loaded correctly, or using stuff like COM or .NET to
mitigate DLL hell, is just in a different league. That is for computer
engineers to take care of, but we are trained as physicists, matematicians,
astronomers, chemists, biologists, or what ever... I am sure that engineers
at Microsoft could do this correctly, but we are not the kind of guys you
would hire :-)

OT: Contrary to common belief, there is no speed advantage of using Fortran
on a modern CPU, because the long pipeline and the hierarchical memory
alleviates the problems with pointer aliasing. C code tends to run faster
then Fortran, often 10 to 20 % faster, and C++ tends to be slightly faster
than C. In 2014, Fortran is only used because it is easier to program for
non-specialists. And besides, correctness is far more important than speed,
which is why we prefer Python or MATLAB in the first place. If you ever see
the argument that Fortran is used because of pointer aliasing, please feel
free to ignore it.


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