[Caml-list] conditional compilation and ocamlbuild

[Caml-list] conditional compilation and ocamlbuild

[Pietro Abate]

Hello list,

I've three modules a.ml, b.ml and common.ml. A and B both
use Common, but Common is compiled with Camlp4MacroParser
to exclude/include part of the code.

The problem I want to include some part of the code when 
I compile A and exclude it when I compile B.

so the canonical way to use Camlp4MacroParser is to add a rule like

<common.ml>: pp(camlp4o Camlp4MacroParser.cmo -DISTRUE)

and when I compile everything I get something like :

$ocamlbuild -classic-display b.byte a.byte
/usr/bin/ocamldep -modules b.ml > b.ml.depends
/usr/bin/ocamldep -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -modules common.ml > common.ml.depends
/usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -o common.cmo common.ml
/usr/bin/ocamlc -c -o b.cmo b.ml
/usr/bin/ocamlc common.cmo b.cmo -o b.byte
/usr/bin/ocamldep -modules a.ml > a.ml.depends
/usr/bin/ocamlc -c -o a.cmo a.ml
/usr/bin/ocamlc common.cmo a.cmo -o a.byte

now, both A and B use common.ml compiled with -DISTRUE .
But this is not what I want.

I'm pretty sure I can't use _tags in this situation. But I'm
not sure how to write a simple myocamlbuild rule to basically
creating two common.cmo. 

One for A as
/usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -o common.cmo common.ml

and one for B as
/usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo' -o common.cmo common.ml

-----------a.ml -------
let a = print_endline (Common.func ())

-----------b.ml -------
let a = print_endline (Common.func ())

----------common.ml -------
let func () =
IFDEF ISTRUE THEN
"is true"
ELSE
"is not true"
END

I guess the idea is to add a rule that says :
if you are compiling A then run the preprocessor with -DISTRUE otherwise
without it. But doing this I want also to force ocamlbuild not to reuse an
existing common.cmo that maybe was compiled from a "different" source...

Of course my real problem is a bit more complicated as in the conditional
compilation process I exclude/include calls an external C library and
I want to avoid linking this external C library to binaries that do not use
it at all ...

pietro
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Re: [Caml-list] conditional compilation and ocamlbuild

[Gabriel Scherer]

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It's a hack, but have you considered symlinking common.ml to a different
name (common_without_distrue, no idea) to bypass the per-name tag
attribution and caching logic of Ocamlbuild?
You could also generate files on the fly (add ocamlbuild rules to generate
common_for_a.ml and common_for_b.ml, then have a and b depend on those
modules).

The problem is that it changes the name of the Common module for a.ml and
b.ml.

On Thu, Jun 2, 2011 at 11:38 AM, Pietro Abate
<Pietro.Abate@pps.jussieu.fr>wrote:

> Hello list,
>
> I've three modules a.ml, b.ml and common.ml. A and B both
> use Common, but Common is compiled with Camlp4MacroParser
> to exclude/include part of the code.
>
> The problem I want to include some part of the code when
> I compile A and exclude it when I compile B.
>
> so the canonical way to use Camlp4MacroParser is to add a rule like
>
> <common.ml>: pp(camlp4o Camlp4MacroParser.cmo -DISTRUE)
>
> and when I compile everything I get something like :
>
> $ocamlbuild -classic-display b.byte a.byte
> /usr/bin/ocamldep -modules b.ml > b.ml.depends
> /usr/bin/ocamldep -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -modules
> common.ml > common.ml.depends
> /usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -o
> common.cmo common.ml
> /usr/bin/ocamlc -c -o b.cmo b.ml
> /usr/bin/ocamlc common.cmo b.cmo -o b.byte
> /usr/bin/ocamldep -modules a.ml > a.ml.depends
> /usr/bin/ocamlc -c -o a.cmo a.ml
> /usr/bin/ocamlc common.cmo a.cmo -o a.byte
>
> now, both A and B use common.ml compiled with -DISTRUE .
> But this is not what I want.
>
> I'm pretty sure I can't use _tags in this situation. But I'm
> not sure how to write a simple myocamlbuild rule to basically
> creating two common.cmo.
>
> One for A as
> /usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -o
> common.cmo common.ml
>
> and one for B as
> /usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo' -o common.cmo
> common.ml
>
> -----------a.ml -------
> let a = print_endline (Common.func ())
>
> -----------b.ml -------
> let a = print_endline (Common.func ())
>
> ----------common.ml -------
> let func () =
> IFDEF ISTRUE THEN
> "is true"
> ELSE
> "is not true"
> END
>
> I guess the idea is to add a rule that says :
> if you are compiling A then run the preprocessor with -DISTRUE otherwise
> without it. But doing this I want also to force ocamlbuild not to reuse an
> existing common.cmo that maybe was compiled from a "different" source...
>
> Of course my real problem is a bit more complicated as in the conditional
> compilation process I exclude/include calls an external C library and
> I want to avoid linking this external C library to binaries that do not use
> it at all ...
>
> pietro
> --
> ----
> http://en.wikipedia.org/wiki/Posting_style
>
> --
> Caml-list mailing list.  Subscription management and archives:
> https://sympa-roc.inria.fr/wws/info/caml-list
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>
>

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Re: [Caml-list] conditional compilation and ocamlbuild

[Pietro Abate]

On Thu, Jun 02, 2011 at 11:49:35AM +0200, Gabriel Scherer wrote:
> It's a hack, but have you considered symlinking common.ml to a different name
> (common_without_distrue, no idea) to bypass the per-name tag attribution and
> caching logic of Ocamlbuild?
> You could also generate files on the fly (add ocamlbuild rules to generate
> common_for_a.ml and common_for_b.ml, then have a and b depend on those
> modules).
> 
> The problem is that it changes the name of the Common module for a.ml and b.ml.

even if this is a hack, I guess this is exactly what I'm going to do. I
could add a more complicated ocamlbuild rule to mangle the source, but I
think it's not worth it...

thanks for the feedback.

> 
> On Thu, Jun 2, 2011 at 11:38 AM, Pietro Abate <Pietro.Abate@pps.jussieu.fr>
> wrote:
> 
>     Hello list,
> 
>     I've three modules a.ml, b.ml and common.ml. A and B both
>     use Common, but Common is compiled with Camlp4MacroParser
>     to exclude/include part of the code.
> 
>     The problem I want to include some part of the code when
>     I compile A and exclude it when I compile B.
> 
>     so the canonical way to use Camlp4MacroParser is to add a rule like
> 
>     <common.ml>: pp(camlp4o Camlp4MacroParser.cmo -DISTRUE)
> 
>     and when I compile everything I get something like :
> 
>     $ocamlbuild -classic-display b.byte a.byte
>     /usr/bin/ocamldep -modules b.ml > b.ml.depends
>     /usr/bin/ocamldep -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -modules
>     common.ml > common.ml.depends
>     /usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -o
>     common.cmo common.ml
>     /usr/bin/ocamlc -c -o b.cmo b.ml
>     /usr/bin/ocamlc common.cmo b.cmo -o b.byte
>     /usr/bin/ocamldep -modules a.ml > a.ml.depends
>     /usr/bin/ocamlc -c -o a.cmo a.ml
>     /usr/bin/ocamlc common.cmo a.cmo -o a.byte
> 
>     now, both A and B use common.ml compiled with -DISTRUE .
>     But this is not what I want.
> 
>     I'm pretty sure I can't use _tags in this situation. But I'm
>     not sure how to write a simple myocamlbuild rule to basically
>     creating two common.cmo.
> 
>     One for A as
>     /usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo -DISTRUE' -o
>     common.cmo common.ml
> 
>     and one for B as
>     /usr/bin/ocamlc -c -pp 'camlp4o Camlp4MacroParser.cmo' -o common.cmo
>     common.ml
> 
>     -----------a.ml -------
>     let a = print_endline (Common.func ())
> 
>     -----------b.ml -------
>     let a = print_endline (Common.func ())
> 
>     ----------common.ml -------
>     let func () =
>     IFDEF ISTRUE THEN
>     "is true"
>     ELSE
>     "is not true"
>     END
> 
>     I guess the idea is to add a rule that says :
>     if you are compiling A then run the preprocessor with -DISTRUE otherwise
>     without it. But doing this I want also to force ocamlbuild not to reuse an
>     existing common.cmo that maybe was compiled from a "different" source...
> 
>     Of course my real problem is a bit more complicated as in the conditional
>     compilation process I exclude/include calls an external C library and
>     I want to avoid linking this external C library to binaries that do not use
>     it at all ...
> 
>     pietro
>     --
>     ----
>     http://en.wikipedia.org/wiki/Posting_style
> 
>     --
>     Caml-list mailing list.  Subscription management and archives:
>     https://sympa-roc.inria.fr/wws/info/caml-list
>     Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
>     Bug reports: http://caml.inria.fr/bin/caml-bugs
> 
> 
> 

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