Nikita Karetnikov <nik...@karetnikov.org> skribis:
>> Remember that (guix build ...) modules must not use Guix modules other
>> than (guix build ...). This is a convention to distinguish between code
>> for the “builder stratum”, and code for the “host stratum”.
>
> OK. But how can I get the location of a package? The needed procedure
> (i.e., 'package-output') is in the host code.
It’s not needed. All that needed is the name of the executable file to wrap.
>> (define* (wrap-program file #:rest variables)
>> ...)
>
> Why do you want to use '#:rest' here? The purpose of 'wrap-program' is
> to export some variables.
For the case where there are have several variables you want to set.
>> export CERT_PATH=$CERT_PATH${CERT_PATH:+:}:/nix/.../share/certs
>
> Could you explain the "$CERT_PATH${CERT_PATH:+:}" part?
The :+ part is to add a colon if and only if $CERT_PATH is non-empty
(info "(bash) Shell Parameter Expansion").
Otherwise you could end up with a value like “:/foo”, but the first
empty element (before the colon) is usually equivalent to “.”, and we
don’t want that.
>> Perhaps the separator string could be optional.
>
> Is it possible to make it optional without creating a separate clause?
No, you’d need an additional clause.
> +(define (wrap-program prog varlst)
> + "Copy PROG to .PROG-real and make PROG a wrapper."
Could you document what the wrapper does, and what the grammar of
‘varlst’ (rather call it ‘vars’) is?
> + (define (export-envvar lst)
‘export-variable’, rather.
> + (define (separate lst delim)
You ‘string-join’ instead:
(string-join '("a" "b") ":")
=> "a:b"
> + ;; TODO: Make SEP optional.
> + (match lst
> + ((var sep '= rest)
> + (format #f "export ~a=\"~a\""
> + var (separate rest sep)))
> +
> + ((var sep 'prefix rest)
> + (format #f "export ~a=\"~a~a${~a~a+~a}$~a\""
> + var (separate rest sep) sep var sep sep var))
> +
> + ((var sep 'suffix rest)
> + (format #f "export ~a=\"$~a${~a~a+~a}~a~a\""
> + var var var sep sep sep (separate rest sep)))))
Good (please indent like other uses of ‘match’ in this file).
> + ;; XXX: Use an absolute filename; remove '-real'.
> + (format #f "#!~a~%~aexec ./.~a-real~%"
> + (which "bash")
> +
> + (fold-right (lambda (x acc)
> + (string-append x "\n" acc))
> + ""
> + (map export-envvar varlst))
string-join
> + prog)) ; XXX: use a real program instead
Just (canonicalize-path prog).
Thanks,
Ludo’.
