ocamlbuild `Circular dependencies'

ocamlbuild `Circular dependencies'

[Christian Sternagel]

I use the following setting for a project:

Within the root directory of the project there are
two subdirectories A and B containing *.ml, *.mli, and *.mly
files.

additionally there is the file A.mllib in A containing all
modules that are in A and B.mllib containing all
modules that are in B.

ocamlbuild -I A A.cma

works fine.

Now B should also result in a lib where some modules in B
depend on modules in A. When trying

ocamlbuild -lib A -Is A,B B.cma

the compilation terminates unsuccessful indicating
some Circular dependencies. However, the Makefile we
used before works fine and there really are no circular
dependencies.

Am I doing something completely wrong here?
Isn't it possible to compile libraries depending on other
libraries?

cheers

christian

Re: [Caml-list] ocamlbuild `Circular dependencies'

[Romain Bardou]

I tried to reproduce a similar set of directories as yours. I couldn't 
get the "circular dependency" error, but I had to compile everything in 
one command line, otherwise the file a.cma (which is in the _build/A 
directory) was deleted before compiling b.cma. The command which I used 
and which worked is:

ocamlbuild -Is A,B a.cma b.cma

I don't really understand how the -lib option works though. Where and 
when does it look for the library x.cma with the "-lib x" option? How 
and what's the semantic of the "+" you can add at the beginning of a 
library name?...

-- 
Romain Bardou

Re: [Caml-list] ocamlbuild `Circular dependencies'

[Christian Sternagel]

On Mon, Jan 28, 2008 at 11:23:29AM +0100, Romain Bardou wrote:
> I tried to reproduce a similar set of directories as yours. I couldn't 
> get the "circular dependency" error, but I had to compile everything in 
> one command line, otherwise the file a.cma (which is in the _build/A 
Today I found out, that we indeed had a circular dependency:

An interface file B.mli used a type A.t, whereas the implementation
file A.ml uses functions from B. When using ocamldep + a Makefile, no
error occurred. But ocamlbuild refused to compile... I guess that is
the right thing to do =)

> directory) was deleted before compiling b.cma. The command which I used 
> and which worked is:
> 
> ocamlbuild -Is A,B a.cma b.cma
> 
> I don't really understand how the -lib option works though. Where and 
> when does it look for the library x.cma with the "-lib x" option? How 
> and what's the semantic of the "+" you can add at the beginning of a 
> library name?...
As far as I know, a `+' means that the following name should be searched
relative to the standard library.

Still my question remains, how one should configure a project
that consists of several libraries and one binary, together
with ocamlbuild. E.g.,

+- prof.dir/
+-+- A/
| +- a.mllib
| +- a1.ml
| +- ...
| +- aN.ml
|
+-+- B/
| +- b.mllib
| +- b1.ml
| +- ...
| +- bN.ml
|
+-+- Main/
  +- main.ml (depending on a.cma and b.cma)

cheers

christian
> 
> -- 
> Romain Bardou
> 
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Re: [Caml-list] ocamlbuild `Circular dependencies'

[Romain Bardou]

 > Still my question remains, how one should configure a project
 > that consists of several libraries and one binary, together
 > with ocamlbuild. E.g.,
 >
 > +- prof.dir/
 > +-+- A/
 > | +- a.mllib
 > | +- a1.ml
 > | +- ...
 > | +- aN.ml
 > |
 > +-+- B/
 > | +- b.mllib
 > | +- b1.ml
 > | +- ...
 > | +- bN.ml
 > |
 > +-+- Main/
 >   +- main.ml (depending on a.cma and b.cma)

Well, is it a problem to compile using:
	ocamlbuild -Is A,B,Main main.byte

If you really want to build libraries independently then maybe you could 
build the cma files, copy them in a "lib" directory which won't be 
included by ocamlbuild (because of "sanitization" restrictions) and then 
use the "-lib" option to use "lib/a.cma" and "lib/b.cma"...

The script would look like this, supposing B depends on A and Main 
depends on A and B (not tested):

#!/bin/sh
ocamlbuild -I A a.cma
cp _build/A/a.cma lib
ocamlbuild -lib lib/a -I B b.cma
cp _build/B/b.cma lib
ocamlbuild -libs lib/a,lib/b -I Main main.byte

-- 
Romain Bardou

Re: [Caml-list] ocamlbuild `Circular dependencies'

[Nicolas Pouillard]

Excerpts from christian.sternagel's message of Mon Jan 28 11:43:09 +0100 2008:
> On Mon, Jan 28, 2008 at 11:23:29AM +0100, Romain Bardou wrote:
> > I tried to reproduce a similar set of directories as yours. I couldn't 
> > get the "circular dependency" error, but I had to compile everything in 
> > one command line, otherwise the file a.cma (which is in the _build/A 
> Today I found out, that we indeed had a circular dependency:
> 
> An interface file B.mli used a type A.t, whereas the implementation
> file A.ml uses functions from B. When using ocamldep + a Makefile, no
> error occurred. But ocamlbuild refused to compile... I guess that is
> the right thing to do =)

Yes  ocamlbuild  treats  your  module (interface + implementation) as a whole.
Then  dependencies  are  computed for modules, so you are in a case that could
be  compiled  but  ocamlbuild  will  refuse  it. I'm a bit reluctant to change
this,  since  I  think  that  the  right  thing to do is to avoid this kind of
semi-cycles.

> > directory) was deleted before compiling b.cma. The command which I used 
> > and which worked is:
> > 
> > ocamlbuild -Is A,B a.cma b.cma
> > 
> > I don't really understand how the -lib option works though. Where and 
> > when does it look for the library x.cma with the "-lib x" option? How 
> > and what's the semantic of the "+" you can add at the beginning of a 
> > library name?...
> As far as I know, a `+' means that the following name should be searched
> relative to the standard library.

All  ocamlbuild  include  directories  must  be  implicit  and relative to the
current  dir.  So  dirs  like ../foo, /foo, +foo, ./foo are forbidden. You can
make  symbolic  link  to avoid the two first cases. If you really need to give
+foo  dir,  please  use non-interpreted compilation flags like -cflags for the
command line and tags like ["ocaml"; "compile"] for a tag based approach.

> Still my question remains, how one should configure a project
> that consists of several libraries and one binary, together
> with ocamlbuild. E.g.,
> 
> +- prof.dir/
> +-+- A/
> | +- a.mllib
> | +- a1.ml
> | +- ...
> | +- aN.ml
> |
> +-+- B/
> | +- b.mllib
> | +- b1.ml
> | +- ...
> | +- bN.ml
> |
> +-+- Main/
>   +- main.ml (depending on a.cma and b.cma)

The simplest thing to do is what you've tried (ocamlbuild -Is A,B Main/main.byte).

But here your mllib's are not used.

If you want to use them as libraries you need a small myocamlbuild.ml like:

$ cat myocamlbuild.ml
open Ocamlbuild_plugin;;
dispatch begin function
| After_rules ->
    ocaml_lib "A/a";
    ocaml_lib "B/b"
| _ -> ()
end

And to tag your files:

$ cat _tags
# tells that main use a and b libs
<Main/main.{byte,native}>: use_a, use_b
# this will avoid the need of command line options to ocamlbuild
"A" or "B": include

$ ocamlbuild Main/main.byte

Cheers,

PS: I've just updated the wiki [1]
[1]: http://brion.inria.fr/gallium/index.php/Using_internal_libraries

-- 
Nicolas Pouillard aka Ertai