Re: ocaml build scripts
Le 12/03/2014 17:06, Robert Lemmen a écrit :
> I have zero knowledge of ocaml, but need to build it with changes as a
> build dependency for something else I am experimenting with. doing that
> I stumbled over something very puzzling, perhaps you could help me
> understand it:
What changes?
> debian/rules in ocaml (3.12.1) calls dh_ocaml, from the package dh-ocaml
> on which it depends. so far so good. dh_ocaml, more specifically
> /usr/bin/ocaml-md5sums, then calls ocamlobjinfo which is part of
> ocaml-nox, but dh-ocaml does not depend on ocaml-nox. not a problem, I
> can set OCAMLOBJINFO in the environment to the ocamlobjinfo which just
> got built by ocaml itself.
Did you try to use the existing package, and apply your changes there?
> but the shebang line on that calls /usr/bin/ocamlrun, which again would
> required ocaml installed. I can even get around that by setting
> OCAMLOBJINFO to "<somepath>/ocamlrun <somepath>/ocamlobjinfo",
> circumventing the shebang.
>
> but ocamlobjinfo seems to call /usr/lib/ocaml/objinfo_helper, which I
> can't seem to find a way around.
/usr/lib/ocaml is the location of the standard library, and it can be
overridden with the OCAMLLIB environment variable (it is documented in
the ocamlrun manpage).
> so to me this looks a bit like dh-ocaml would need a dependency on
> ocaml, which of course is terrible because of the chicken-and-egg
> bootstrapping issue. But I do not understand how this can ever build in
> the absence of ocaml on the build machine. what am I missing?
As you figured out, dh-ocaml depending on ocaml would imply a
build-dependency loop (ocaml build-depends on dh-ocaml...) for very
little benefit. Indeed, in practice, they are always installed together
(when dh_ocaml is called), except in the specific case of ocaml itself,
where an existing ocaml installation would be useless anyway.
Besides, there are other things in dh-ocaml, such as scripts for
interacting with Alioth or the OCaml packaging policy and documentation,
that are useful even if ocaml-nox is not installed.
BTW, in ocaml's debian/rules, there is:
> # Environment variable for dh_ocaml
> export OCAMLOBJINFO = OCAMLLIB=tools boot/ocamlrun tools/objinfo
Cheers,
--
Stéphane
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