[Distutils] PEP 426 updated based on last round of discussion

Oscar Benjamin oscar.j.benjamin at gmail.com
Wed Jul 17 14:40:02 CEST 2013

On 17 July 2013 13:17, Nick Coghlan <ncoghlan at gmail.com> wrote:
> That said, the new metadata standard does deliberately include a few
> pieces intended to make such things easier to define:
> 1. The extensions concept - using a structured data format like JSON
> makes it much easier for platform specific tools (or even pip itself)
> to say "declare this metadata, and we will run these commands
> automatically"

Okay, so this is where you can put the "I need a [specific]
C-compiler" information. Then a pip alternative (or a future pip) that
knew more about C compilation could respond appropriately.

The PEP doesn't explicitly say anything about how a tool should handle
unrecognised metadata extensions; it seems fairly obvious to me that
they are supposed to be ignored but perhaps this should be explicitly

On the other hand it would be useful to be able to say: if you don't
understand my "fortran" metadata extension then you don't know how to
install/build this distribution. Is there a way e.g. to indicate a
build/install dependency on the tool understanding some section in the
extension metadata, or that an extension is compulsory somehow?

Then a user could do:
$ pip install autocont
Error installing "autocont": required extension "fortran" not understood.
See http://pypa.org/list_of_known_extensions.htm for more information.


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