Nikita Karetnikov <nik...@karetnikov.org> skribis:
>> wrapProgram $out/bin/guile-snarf --prefix PATH : "${gawk}/bin"
>
> How can I get the output of a package?
With the recently-added ‘package-output’ (singular):
--8<---------------cut here---------------start------------->8---
scheme@(guile-user)> (package-output s binutils "out")
$2 = "/nix/store/bfh5c2a4is27jdmc811fp6g0jfac7fiw-binutils-2.22"
scheme@(guile-user)> (package-output s binutils "lib")
$3 = "/nix/store/n29brzqlhjkzww51labk9anx493gl4d3-binutils-2.22-lib"
--8<---------------cut here---------------end--------------->8---
Under the hood it calls ‘package-derivation’, which does the actual
output path computation.
>> #!/bin/sh
>> export PATH="/nix/store/...-gawk/bin:$PATH"
>> exec ./.guile-snarf-real "$@"
>
> Should it be saved as 'guile-snarf'? And I have to use rename(2),
> right?
You first rename the wrapped program, then create the wrapper as above,
and finally chmod it so that it’s executable.
> What should I use to handle prefixes (e.g., a keyword, a simple
> argument)? Should they be case insensitive?
Good question. The thing is that sometimes you want to affect several
environment variables. Maybe something like:
(define* (wrap-program file #:rest variables)
...)
Where each rest argument has a form like this:
("PATH" ":" prefix ("/nix/.../foo/bin" "/nix/.../bar/bin"))
Instead of ‘prefix’, users could ask for ‘prefix’ (prepend to the search
path) or ‘=’ (set the search path to exactly that value.)
WDYT?
Ludo’.
