Hi Catonano,
> I am experimenting with this line
>
> (system* "guile" "-c" "(use-modules (commonmark)) (exit ((lambda () 0)))")
>
> If it finds the module it returns 0
>
> Otherwise it returns a different number
>
> I copied some bits for a configure script for a Guile project instrumented
> with the Autotools
>
> I could use an example of usage of "status:Exit-val"
>
> The Guile manual says:
>
> Return the exit status value, as would be set if a process ended
> normally through a call to ‘exit’ or ‘_exit’, if any, otherwise
> ‘#f’.
>
> this is not enouhg for me to understand
>
> In which scenario is thhis function supposed to be used ? In order to do
> what ?
> An example would be of great help
With this procedure you can obtain the return status for “system*”.
Here’s an example:
--8<---------------cut here---------------start------------->8---
(display "Checking for commonmarl...")
(let ((status
(parameterize ((current-error-port (%make-void-port "w")))
(status:exit-val (system* "guile" "-c"
"(begin (use-modules (commonmarl))
(exit 0))")))))
(display (if (zero? status)
"Success!"
"Oh no!"))
(newline))
--8<---------------cut here---------------end--------------->8---
> Anyway: Is this the idiomatic way ?
>
> Or maybe I should use some try catch form wrapping some module loading
> instruction ?
> Without launching a different guile process ?
There are advantages to spawning a new guile process. One is that
whatever modules you may have loaded for your tool won’t affect the
check. It’s possible that your tool bundles a bunch of modules, but
when Guile is spawned in a pure environment it won’t be able to load
these modules. You may want to fail the configure test then.
On the other hand, it’s ugly to pass a Guile programme as a string to
system*, when you could do that instead with pure Guile. I haven’t
thought enough about this to give a recommendation either way.
--
Ricardo
