[Caml-list] Re: Conditional BuildDepends in OASIS

[Sylvain Le Gall <sylvain@le-gall.net>]

On 26-10-2012, Dario Teixeira <darioteixeira@yahoo.com> wrote:
> Hi,
>
>
> Thanks for the suggestions, Anil!
>
>> However, your use case seems a little different, as I presume the
>> external interface of pgocaml doesn't vary by your choice of Extlib
>> or Batteries?
>
> Indeed.
>
>> Despite this, it might be easier just to define a "pgocaml.batteries"
>> and "pgocaml.extlib" and leave the choice with the user as to which
>> one they would like to select.  You can make the dependency optional
>> at compile time so the package doesn't generated; e.g.
>> 
>> Library cohttp_lwt_unix
>>   Build$: flag(lwt)
>>   Install$: flag(lwt)
>>   Path: lwt
>>   Findlibname: lwt
>>   FindlibParent: cohttp
>>   BuildDepends: lwt.unix, uri, cohttp, lwt.ssl, lwt.syntax
>>   Modules: Cohttp_lwt_unix, (etc...)
>
> That would be a satisfactory solution.  I did run into a different problem, though.
> I told OASIS that "pgocaml.batteries" and "pgocaml.extlib" should have "pgocaml"
> as their findlib parent (fragment below).  Unfortunately, OASIS complains that
> library "pgocaml" does not exist.  How would I tell OASIS that "pgocaml" is a
> dummy library?
>
> Flag "batteries"
>   Description: Use Batteries
>   Default: true
>
> Library "pgocaml_batteries"
>   Build$:               flag(batteries)
>   Install$:             flag(batteries)
>   Path:                 src
>   Modules:              PGOCaml
>   BuildDepends:         calendar, batteries
>   ByteOpt+:             -ppopt -DUSE_BATTERIES
>   NativeOpt+:           -ppopt -DUSE_BATTERIES
>   FindlibParent:        pgocaml
>   Findlibname:          batteries
>

Having pgocaml.batteries and pgocaml.extlib is the best solution,
depending on a flag is perfect. Congrat to have find it yourself ;-)
(don't forget to CC me directly if you want a quicker response, I am a
little bit overloaded and don't spend much time reading caml-list).

Concerning FindlibParent that complains about non-existing pgocaml, you
should use FindlibContainers rather than FindlibParent.

E.g:

Library "pgocaml_batteries"
  Build$:               flag(batteries)
  Install$:             flag(batteries)
  Path:                 src
  Modules:              PGOCaml
  BuildDepends:         calendar, batteries
  ByteOpt+:             -ppopt -DUSE_BATTERIES
  NativeOpt+:           -ppopt -DUSE_BATTERIES
  FindlibContainers:    pgocaml
  Findlibname:          batteries

Containers are virtual by default...

Although, this something I am not proud of and in the upcoming oasis 0.4.0 everything
will go to "FindlibName: pgocaml.batteries" and OASIS will sort
parent/containers/library itself.

Cheers,
Sylvain Le Gall
-- 
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