[Distutils] EasyInstall and build-time dependencies

Ronald Oussoren ronaldoussoren at mac.com
Fri Jun 10 17:12:13 CEST 2005

On 9-jun-2005, at 13:14, Phillip J. Eby wrote:

> At 12:36 PM 6/9/2005 -0700, Ronald Oussoren wrote:
>> Are there any plans to teach EasyInstall about build time
>> dependencies? And example of this would be the dependency of PIL on
>> libjpeg and libtiff.
> Yes and no.  I plan to refactor EasyInstall so that packages that  
> want to, can use its find-and-download capabilities to install  
> their own dependencies of that sort. However, if PyPI ever includes  
> metadata that EasyInstall could consult about a package's non- 
> Python dependencies, it could be used to inform the user.

That's good enough for me.  For the major reason for adding explicit  
dependencies to normal C libraries would be to avoid strange failures  
when installing a package through EasyInstall. It would be nice if  
EasyInstall could give a nice message about missing C libraries, that  
obviously requires the cooperation of the packages.

> There's also the possibility that we could enhance Eggs to be able  
> to deal with headers and libraries, and then create distutils  
> wrappers for building libraries or finding them on the system.   
> Then, PIL could depend on "py-libjpeg" and "py-libtiff" wrappers  
> that could be used to find the headers and libraries for compiling  
> the PIL extensions.

My major gripe about PIL's build procedure is that it *optionally*  
depends on some graphics libraries. This means that I end up with a  
(for me at least) mostly useles version of PIL if I forget to install  
libjpeg first.

It's amazing how little code and infrastructure is needed to build  
CPAN-like functionality for Python. Keep up the good work.


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