* [bug#40365] [PATCH] guix: Improve docstring of wrap-program.
2020-04-01 5:29 [bug#40365] [PATCH] guix: Improve docstring of wrap-program Brendan Tildesley
@ 2020-11-21 10:17 ` Christopher Baines
0 siblings, 0 replies; 2+ messages in thread
From: Christopher Baines @ 2020-11-21 10:17 UTC (permalink / raw)
To: Brendan Tildesley; +Cc: 40365
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Brendan Tildesley <mail@brendan.scot> writes:
> * guix/build/utils.scm (wrap-progran): Add an explanation for POSITION. Change
> 'DIRECTORIES' to 'VALUES' since an environment variable might not only be
> paths.'
> ---
> guix/build/utils.scm | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
Thanks Brendan, and apologies that it's taken a while to review this.
I made some tweaks to end up with this:
(define* (wrap-program prog #:rest vars)
- "Make a wrapper for PROG. VARS should look like this:
+ "Make a wrapper for PROG. VARS is a list of lists that should look like this:
- '(VARIABLE DELIMITER POSITION LIST-OF-DIRECTORIES)
+ '(VARIABLE DELIMITER POSITION LIST-OF-VALUES)
where DELIMITER is optional. ':' will be used if DELIMITER is not given.
+POSITION is a symbol, either =, prefix, or suffix that selects how the
+LIST-OF-VALUES are consolidated with the value of VARIABLE at the time the
+wrapped program is run. prefix and suffix each result in including values
+from the users environment either before or after LIST-OF-VALUES respectively,
+whereas = replaces any existing value for VARIABLE. It is important to
+understand how each variable is used by the program so that the correct choice
+can be made.
+
I'll hopefully describe why below. Anyway, let me know what you think,
I'm happy to push some improvements to this.
There's a bit of a cost to updating this file, since I believe changing
it will effectively trigger every Guix package's derivation to change,
hence it will need to be done on the core-updates branch.
> diff --git a/guix/build/utils.scm b/guix/build/utils.scm
> index b8be73ead4..ba4d1d8657 100644
> --- a/guix/build/utils.scm
> +++ b/guix/build/utils.scm
> @@ -5,6 +5,7 @@
> ;;; Copyright © 2015, 2018 Mark H Weaver <mhw@netris.org>
> ;;; Copyright © 2018 Arun Isaac <arunisaac@systemreboot.net>
> ;;; Copyright © 2018, 2019 Ricardo Wurmus <rekado@elephly.net>
> +;;; Copyright © 2020 Brendan Tildesley <mail@brendan.scot>
> ;;;
> ;;; This file is part of GNU Guix.
> ;;;
> @@ -1114,13 +1115,20 @@ known as `nuke-refs' in Nixpkgs."
> (string-suffix? "-real" base)))))
>
> (define* (wrap-program prog #:rest vars)
> - "Make a wrapper for PROG. VARS should look like this:
> + "Make a wrapper for PROG. VARS is a list of lists that should look like this:
I'm not sure I'd describe vars as a list of lists, I think I see what
you're getting at, in that there can be more than one thing in vars, but
from the perspective of a user of this procedure, you don't pass in a
list of list, just one or more arguments at the end.
>
> - '(VARIABLE DELIMITER POSITION LIST-OF-DIRECTORIES)
> + '(VARIABLE DELIMITER POSITION LIST-OF-VALUES)
>
> where DELIMITER is optional. ':' will be used if DELIMITER is not given.
> -
> -For example, this command:
> +POSITION is a Scheme symbol of either =, prefix, or suffix that selects how
> +the export VARIABLE line is formatted. prefix and suffix each result in
Rather than talking about formatting here, I tried to say something
about "consolidation", although maybe that's too complicated.
> +including values from the users environment either after or before VALUE,
> +whereas = overshadows any existing value, preventing the users environment
> +from 'infecting' the wrapped programs environment. It is important to
> +understand how each variable is used by the program so that the correct choice
> +can be made. Otherwise, the program could malfunction in unexpected ways on a
> +different persons computer due to a difference in the inherited environment
> +variables. For example, this command:
I'm not sure about including this "Otherwise ..." bit, I think what you
say prior is sufficient.
>
> (wrap-program \"foo\"
> '(\"PATH\" \":\" = (\"/gnu/.../bar/bin\"))
Thanks again,
Chris
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