RE: [Caml-list] Libraries exporting external definitions in modules

[David Allsopp <dra-news@metastack.com>]

Thanks for the replies!

Gerd Stolpmann wrote:
> There is an easy workaround: Don't put the external declaration into the
> mli, just a val. When installing the library, take care to also include
> the cmx file. This way, the extra function wrapper can be eliminated by
> the automatic inliner of ocamlopt.

Ah, I didn't realise that that was one of the optimisations which installing the .cmx file allows. In fact, that seems to be a good case for *never* using external in the .cmi file, as that way you have transparent control over a future version which just might need to put an OCaml wrapper around the stub.

> Of course, this works only for native code.

True, but the introduction of native dynlink (on most platforms, at least) does seem to make worrying about very small optimisations (i.e. non-algorithmic) for bytecode silly :o)

Markus Mottl wrote:
> This bug report also describes this problem:
> http://caml.inria.fr/mantis/view.php?id=4166

ocamldoc/trunk/manual/cmds/intf-c.etex was updated by Damien at the end of November with a warning in the explanation of the [external] keyword that this can happen (was glad I spotted that *before* attaching a documentation patch to your PR!)

> I think this should get fixed.  Though there is an easy (though slightly
> less efficient) workaround, this problem is pretty hard to identify,
> especially for people who have never seen it.

Judging by Jacques note connecting it to PR#6063 it will be soon - though given that installing the .cmx files enables the optimisation as well, I'm wondering if never using [external] in .mli files is actually the better route?


David