Re: [Caml-list] Obtaining module dependencies from within OCamlbuild plugin

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

In OCamlbuild, most of the dependencies are detected dynamically while
the compilation runs (typically the process of producing a target (eg.
foo.cma) will run code that will decide to recursively produce lots of
targets (eg. modules listed in foo.mllib), and those are the dynamic
dependencies). Command_deps_of_tags returns the static dependencies
that have been specified by tags, by using Command.dep and
Command.pdep to associate dependencies to specific tags.

You cannot obtain the set of dependencies of a target without actually
trying to build it. (If you were interested in this for performance
reason, a reasonable idea would be to cache the dependencies of the
last build and replay them optimistically, but I assume that's not
your point here.)


On Tue, Feb 3, 2015 at 9:01 PM, Dario Teixeira
<dario.teixeira@nleyten.com> wrote:
> Hi,
>
> I'm trying to manipulate a project's dependencies from within an OCamlbuild
> plugin, and one prerequisite is obtaining the current set of dependencies
> for a given module.  For instance, to obtain the set of dependencies for
> module "src/foo_c.ml", one could expect to invoke the following from within
> the After_rules hook of myocamlbuild.ml:
>
>   Command.deps_of_tags (tags_of_pathname "src/foo_c.ml")
>
> This always returns an empty list, however.  The same holds if one tries
> to narrow the list of tags to just the filename:
>
>   Command.deps_of_tags (Tags.of_list ["file:src/foo_c.ml"])
>
> One possible explanation for this behaviour is that the set of dependencies
> has not been computed yet when the After_rules hook is invoked.  Is that the
> case, or am I missing something altogether different?  Either way, how do I
> obtain the set of dependencies?
>
> Thanks in advance for your attention!
> Kind regards,
> Dario Teixeira
>
>
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