Re: ocamlbuild bug and questions Was: Re: [Caml-list] ocamlbuild: using *.itarget with flags

["Nicolas Pouillard" <nicolas.pouillard@gmail.com>]

Excerpts from viktor.tron.ml's message of Thu Nov 22 17:36:14 +0100 2007:
> On 21/11/2007, Nicolas Pouillard < nicolas.pouillard@gmail.com> wrote:
> >
> > Excerpts from hmf's message of Wed Nov 21 12:30:28 +0100 2007:
> > > The manual states that in the *.itarget
> > > files a comment is either a blank or dash.
> > > Does this mean:
> > >
> > > - comment here
> > >
> > > is a comment? If so, it does not seem
> > > to work.
> >
> > The manual is wrong on that point, it's a sharp (#) not a dash (-).
> >
> > # comment here
> >
> 
> I also noticed that. Plus what seems to be a couple of bugs?
> 
> $ echo -n '# comment here' > _tags
> $ ocamlbuild target
> Lexical analysis error: Bad key in configuration line at line 1 (from file:
> "_tags")

Yes your right, comments should end by a new line (I fix that).

> or even worse
> 
> $ echo -n '# comment here:' > _tags
> $ ocamlbuild target
> Failure: lexing: empty token.

Yes that's the same one.

> Also:  I had a number of question concerning ocamlbuild in my recent post
> about c libs from ocaml.
> I elaborate them here, but see my original post for the context.
> Does anyone have an illuminating insight?
> 
> ---
> 
> *  I still don't know the most basic thing, how to build an output-obj o
> file.

That's  not  "the  most basic thing" for the average OCaml programmer I think.
Ocamlbuild  don't  have  such  a  rule  by  default (I think it will). However
define your own custom rule is really feasible.

(* something like that, but I've not tested *)
rule "the rule name"
  ~deps:["foo.cmo"; "libbar.a"(*...*)]
  ~prods:["obj.o"(*...*)]
  begin fun _ _ ->
    Cmd(S[V"OCAMLC"; A"-output-obj"; A"-o"; Px"obj.o"; P"foo.cmo"; P"libbar.a"(*...*)])
  end;

> *  I found no way to convince ocamlbuild to use the local library (in this
> example we build
> ocamlbuild foo.cmxa
> and then would simply want
> ocamlopt -o foo foo.cmxa foo_wrapper.ml
> but 'ocamlbuild foo_wrapper.native' rebuilds it all the same

in the myocamlbuild.ml you have to declare the library:

ocaml_lib "foo"

and in the _tags file:

"foo_wrapper.native": use_foo

> * I don't know what the possible tags are, how I add them.

They are implicitly declared, for instance if you add:

flag ["ocaml"; "link"; "byte"; "mytag"] (S[A"-cclib"; A"mycopt"]);

You  can  then  tag  some  .byte files with mytag, -cclib mycopt flags will be
added at link time.

> * If I use a syntax extension which has to be build, adding the pp... tag
> does not create a dependency which is checked. I don't know how to add this
> dependency.

Use a dep declaration with same tags and then files that needs to be built.

dep ["ocaml"; "pp"; ...] ["myextension.cmo"]

> Help appreciated, but probably a  more detailed manual will solve
> this with time.

The wiki [1] talk about using syntax extension.

[1]: http://brion.inria.fr/gallium/index.php/A_plugin_for_camlp4_syntax_extension_%28pa_openin%29
-- 
Nicolas Pouillard aka Ertai