Re: [Numpy-discussion] include file location and .eggs

[<kon...@la...>]

On Jan 19, 2006, at 18:31, Andrew Straw wrote:

> For me, and I suspect for most others in favor of the new way, the
> answer boils down to using eggs with out-of-the box numpy. Eggs are =20=

> the
...

Thanks for explaining this issue in some detail!

> =3D Why can't eggs use traditional include locations? =3D
> Multiple version support. Using eggs, it is possible to have multiple
> versions of the same distribution, such as numpy, installed within a
> single Python installation. (I use "distribution" to mean =20
> collection of

How is multiple version support in eggs supposed to work in the case =20
of packages that contain C modules?

Let me give a concrete example: Numeric, ScientificPython, and MMTK. =20
Numeric provides a C API through its header files. ScientificPython =20
and MMTK both contain C modules that depend on that C API. =20
ScientificPython also provides a C API for two of its modules, which =20
in turn MMTK depends on.

Suppose I would like to have both Numeric 23.5 and Numeric 24.2 on my =20=

machine, and also Scientific 2.4.2 and Scientific 2.5.1. I would then =20=

need four sets of the binary modules of Scientific:

1) 2.4.2 for Numeric 23.5
2) 2.4.2 for Numeric 24.2
3) 2.5.1 for Numeric 23.5
4) 2.5.1 for Numeric 24.2

I would also need four sets of the binary modules of MMTK, assuming =20
that I am happy with just one version of MMTK.

Unless some mechanism (which would have to be part of egg =20
construction or egg installation) makes sure that the correct =20
binaries are used for the particular combination of versions that I =20
wish to use, I will end up having lots of mysterious crashes =20
resulting from incompatible binary versions.

If the egg mechanism does take care of such dependencies, then it =20
could easily (and thus should) take care of selecting the right =20
combination of header files. If it doesn't, then it should not be =20
used at all for packages containing C or Pyrex modules, and packages =20
like numpy should better not accomodate to eggs because in the long =20
run that will only cause support headaches.

Konrad.
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Konrad Hinsen
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