bug#22808: Add a function to simplify many of the new python2-foo definitions

[ludo@gnu.org (Ludovic Courtès)]

Efraim Flashner <efraim@flashner.co.il> skribis:

> On Tue, Apr 26, 2016 at 11:54:28AM +0200, Ludovic Courtès wrote:
>> ludo@gnu.org (Ludovic Courtès) skribis:

[...]

>> What about this:
>> 
>
>> --- a/gnu/packages/python.scm
>> +++ b/gnu/packages/python.scm
>> @@ -345,6 +345,14 @@ instead of @command{python3}.")))
>>  (define-public python-wrapper (wrap-python3 python))
>>  (define-public python-minimal-wrapper (wrap-python3 python-minimal))
>>  
>> +(define (package-with-python2+setuptools p)
>> +  (let ((base (package-with-python2 (strip-python2-variant p))))
>> +    (package
>> +      (inherit base)
>> +      (native-inputs `(("python2-setuptools" ,python2-setuptools)
>> +                       ,@(package-native-inputs base))))))
>> +
>> +\f
>>  (define-public python-psutil
>>    (package
>>      (name "python-psutil")
>
>> 
>> Then we need to change all the occurrences of this pattern to use this
>> new procedure.
>> 
>> Thoughts?
>> 
>> Ludo’.
>
> Would we still need the properties field in python-foo?

Yes.

> What would this mean for packages that need python2-setuptools and other
> python2- specific packages? Specifically, would all the calls to
> package-native-inputs cause a slowdown in computing the package?

It wouldn’t change anything, since this exact same pattern is already
used in many different places in python.scm (search for
“python2-setuptools” and you’ll see :-)).  It would simply allow us to
factorize it.

Ludo’.