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From: "Ludovic Courtès" <ludo@gnu.org>
To: Maxime Devos <maximedevos@telenet.be>
Cc: guix-devel@gnu.org
Subject: Re: [PATCH RFC 0/4] Getting rid of input labels?
Date: Wed, 26 May 2021 15:43:31 +0200	[thread overview]
Message-ID: <87k0nlvce4.fsf@gnu.org> (raw)
In-Reply-To: <1dbbcac6e26ae1df767a813698e92cbe364d88fa.camel@telenet.be> (Maxime Devos's message of "Thu, 20 May 2021 21:31:34 +0200")

Hi Maxime,

Maxime Devos <maximedevos@telenet.be> skribis:

> Ludovic Courtès schreef op do 20-05-2021 om 16:58 [+0200]:
>> Hello Guix!
>> 
>> Here’s a proposal for a soft revolution: getting rid of input labels
>> in package definitions.  Instead of writing: [...]
>>    
>> one can write:
>> 
>>     (native-inputs (list autoconf automake pkg-config guile-3.0))
>> [...]
>
> This concept LGTM (but I haven't looked closely at the patches), but
> as noted on #guix, some issues with eliminating labels completely:
>
> A package definition of P may require both Q@1.0 and Q@2.0 as inputs,
> in which case a ‘label collision’ would be created if we generate
> labels package-name. More specifically, I'm thinking of packaging
> go-ipfs-migrations (or what's its name ...). It would be a good idea
> to add an (additional?) test to actually try to migrate from
> go-ipfs@first-version to go-ipfs@another-version.

Keep in mind that labels exist to make it easier to refer to a specific
input from the build side—in a phase, configure flag, etc.

In many cases, you don’t need the ability to refer to a specific input;
you just need all the inputs to contribute to search path environment
variables, and that’s enough.  A “label collision” does not matter at
all in this case.

In some cases, you do need to refer to a specific input, as in:

  #:configure-flags (list (string-append "--with-gmp-prefix="
                                         (assoc-ref %build-inputs "gmp")))

In this case, there are now two options:

  1. Arrange so that label is unique among your inputs, as is already
     the case.

  2. Use a gexp instead (possible on ‘core-updates’) like so:

       #:configure-flags #~(list (string-append "--with-gmp-prefix=" #$gmp))

     or, to allow for inheritance:

       #:configure-flags #~(list (string-append "--with-gmp-prefix="
                                                #$@(assoc-ref
                                                    (package-inputs this-package)
                                                    "gmp")))

     The second variant is ugly, but we could provide helpers to make it
     prettier.

Do you think there are unaddressed issues with go-ipfs-migrations?

Thanks for your feedback!

Ludo’.


  reply	other threads:[~2021-05-26 13:43 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-20 14:58 [PATCH RFC 0/4] Getting rid of input labels? Ludovic Courtès
2021-05-20 14:58 ` [PATCH RFC 1/4] records: Support field sanitizers Ludovic Courtès
2021-05-20 14:58 ` [PATCH RFC 2/4] DRAFT packages: Allow inputs to be plain package lists Ludovic Courtès
2021-05-20 14:58 ` [PATCH RFC 3/4] DRAFT gnu: Change inputs of core packages to plain lists Ludovic Courtès
2021-05-20 14:58 ` [PATCH RFC 4/4] DRAFT lint: Add 'input-labels' checker Ludovic Courtès
2021-05-20 16:19 ` [PATCH RFC 0/4] Getting rid of input labels? Vincent Legoll
2021-05-26 13:35   ` Ludovic Courtès
2021-05-20 19:31 ` Maxime Devos
2021-05-26 13:43   ` Ludovic Courtès [this message]
2021-05-27 19:02     ` Maxime Devos
2021-05-21 15:35 ` Nicolas Goaziou
2021-05-26 14:02   ` Ludovic Courtès
2021-05-30 16:23     ` Ryan Prior
2021-06-08 13:05       ` Ludovic Courtès
2021-06-10 21:39 ` Ludovic Courtès

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