Re: [Caml-list] glob-ing dependencies for a custom ocamlbuild rule

[Gabriel Scherer <gabriel.scherer@gmail.com>]

Ocamlbuild distinguishes "static dependencies", which are expressed in
the ~deps argument of the rule declaration, and "dynamic dependencies"
which are files required by the rule command.

The notion of pattern accepted for static dependencies is indeed
rather rigid (less expressive than the patterns used in the _tags
file), and what you have in mind does not work. The supported patterns
are deterministic: given one file, there is a unique way a pattern can
match, and a pattern is instantiated into a single file by any
substitution environment. There is a good reason for that: it is not
clear what the semantics of your proposal would be. Indeed, ocamlbuild
tries to recursively build all static dependencies before deciding to
apply a rule, but what does it mean to build all **/*.mo? Listing the
one that exist in the source directory is easy, but how would you
guess which one to try to build recursively using other rules?

Notions such as "all files matching P in this directory" are not
stable to the replacement of a source file by an intermediate target:
for example if tomorrow you decide that one of the .mo file will be
itself pre-processed from a .mo.pp file, it won't be seen by a
existing-file globbing technique anymore. You have a lot of
flexibility in the behaviors you implement in the build command, so
you can easily do the matching there and "build" those files, but it
will result in a relatively fragile rule; this is you decision to
make, and not in the path of least resistance.


On Tue, Apr 12, 2016 at 8:00 AM, Christoph Höger
<christoph.hoeger@tu-berlin.de> wrote:
> Dear all,
>
> I want to write a custom ocamlbuild rule that basically combines all
> source files from a given (sub-)directory and thus depends on these files.
>
> However, the following does not work:
>
>         rule "normalize (preprocess) a Modelica library"
>           ~prods:["%.modlib.impl"; "%.modlib.sign"]
>           ~deps:["%.modlib/**/*.mo"; "%.modlib.depends"]
>           ~doc:"Preprocesses a Modelica library"
>           modlibc_command
>
> It seems that the rule does not expand the pattern in the dependency. Is
> there a way to achieve something similar? It would be a major PITA to
> add all these files manually...
>
> regards,
>
> Christoph
> --
> Christoph Höger
>
> Technische Universität Berlin
> Fakultät IV - Elektrotechnik und Informatik
> Übersetzerbau und Programmiersprachen
>
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>
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> E-Mail: christoph.hoeger@tu-berlin.de
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