bug#22437: Fixing package-with-python2

[Ludovic Courtès]

Ricardo Wurmus <address@hidden> skribis:

> Efraim Flashner <address@hidden> writes:
>
>> On Wed, 03 Feb 2016 09:47:15 +0100
>> address@hidden (Ludovic Courtès) wrote:
>>
>>> address@hidden (Ludovic Courtès) skribis:
>>> 
>>> > 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))))))
>>
>> This part I don't get. What's the period for?
>
> The “properties” field holds a regular alist.  Here the alist has one
> entry (a pair) with a symbol “python2-variant” as the key, and “,(delay
> python2-foobar)” as its value.
>
> The period is needed for the “dotted list” syntax, which is used to
> distinguish a pair (or an improper list) from a well-formed list.

This is a relic of the old days and probably kind of confusing to
newcomers, but since we started making this field an alist, let’s keep
it this way.

Ludo’.