Re: Fixing package-with-python2

[Efraim Flashner <efraim@flashner.co.il>]

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On Mon, 01 Feb 2016 23:07:40 +0100
ludo@gnu.org (Ludovic Courtès) wrote:

> 
> An idea I haven’t taken the time to test yet would be to use
> ‘properties’:
> 
>   (define python-foobar   ;with Python 3
>     (package
>       (name "foobar")
>       ;; Specify which Python 2 variant to use.
>       (properties `((python2-variant . ,(delay python2-foobar))))))
> 
>   (define python2-foobar
>     (package (inherit python-foobar)
>       ;; … stuff beyond the mechanical python 2→3 switch…
>       ))
> 
> ‘package-with-python2’ would honor this ‘python2-variant’ property.
> 
> Thoughts?
> 
> Ludo’.

I like a lot that it should remove the need to propagate the special python2-
packages all the way out to the leaf packages. What else could we use this
for? minimal/bootstrap versions?

"The python people" have said that one day python4 will happen and they don't
plan on having it be as much of a break like the python2->python3 change was.
package-with-explicit-python is already set up to handle having a main
package definition and multiple automated definitions.

I prefer when define-public is the start of a package definition, but here's
an idea I just had about refactoring out the common parts of python packages.

(let*
  (name "python-foobar")
  (version "1.2.3")
  ...
  (define-public python3-foobar
    (package-with-python3 python-foobar)
  (define-public python2-foobar
    (package (inherit (package-with-python2 python-foobar))
    (native-inputs
     `(("python2-setuptools" ,python2-setuptools))
       ,@(package-native-inputs foobar)))))
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Efraim Flashner   <efraim@flashner.co.il>   אפרים פלשנר
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