ocamlbuild and installed modules and libraries

ocamlbuild and installed modules and libraries

[Daniel Bünzli]

Hello,

Is it possible to specify a single installed module (instead of a lib)  
for link time ? That is is there something like -lib but for module so  
that I can type :

ocamlbuild -I +xmlm -mod xmlm test.native

where test.ml uses the xmlm module

And what about having special tags use_lib_$LIB and use_mod_$MOD that  
automatically create rules to use libraries $LIB.cm(x)a and module  
$MOD.cm(o|x) so that just the appropriate -I to find the files has to  
be specified. In most cases having to use a plugin just for that seems  
overkill. Or is there another way ?

Best,

Daniel

Re: [Caml-list] ocamlbuild and installed modules and libraries

[Nicolas Pouillard]

Excerpts from daniel.buenzli's message of Sun Nov 16 19:22:02 +0100 2008:
> Hello,
> 
> Is it possible to specify a single installed module (instead of a lib)  
> for link time ? That is is there something like -lib but for module so  
> that I can type :
> 
> ocamlbuild -I +xmlm -mod xmlm test.native
> 
> where test.ml uses the xmlm module

This would make sense, but I would prefer not to push things in this
direction. Options like -lib,-cflag,-lflag... are intended to be used
only in a quick hack usage, indeed they are global and tags are much
more powerful.

> And what about having special tags use_lib_$LIB and use_mod_$MOD that  
> automatically create rules to use libraries $LIB.cm(x)a and module  
> $MOD.cm(o|x) so that just the appropriate -I to find the files has to  
> be specified. In most cases having to use a plugin just for that seems  
> overkill. Or is there another way ?

I'm a bit uncomfortable with this kind of dynamic or special tags.

However the simplest solution to your problem is probably one of those:

  1/ ocamlbuild -cflags -I,+xmlm,xmlm.cmx test.native

  2/ ln -s <sources-of-xmlm> xmlm
     ocamlbuild -I xmlm test.native

  3/ ln -s $(ocamlc -where)/xmlm .
     ocamlbuild -tag_line '"xmlm": not_hygienic' -I xmlm test.native

Hope that helps,

-- 
Nicolas Pouillard aka Ertai

Re: [Caml-list] ocamlbuild and installed modules and libraries

[Daniel Bünzli]

Le 16 nov. 08 à 21:37, Nicolas Pouillard a écrit :

> I'm a bit uncomfortable with this kind of dynamic or special tags.
>
> However the simplest solution to your problem is probably one of  
> those:
>
>  1/ ocamlbuild -cflags -I,+xmlm,xmlm.cmx test.native

You meant,

> ocamlbuild -cflags -I,+xmlm -lflags -I,+xmlm,xmlm.cmx test.native


I still think using ocamlbuild with installed libraries/modules is a  
little bit problematic. If we have to do it that way [1] we are hard- 
coding the location of the library in the plugin which doesn't feel  
right.

For me there should be (1) a way of defining the dependency on a  
module/library (hopefully without needing a plugin) and (2) a way of  
defining its location (-I). These two aspects should be decoupled.  
This makes it easier to drive the installation process in build  
scripts by using environment variables, i.e. I just need
to specify the location of the module/library I depend on via a  
suitable -I $DEPDIR to compile the sources.

Best,

Daniel

[1] http://brion.inria.fr/gallium/index.php/Using_an_external_library

Re: [Caml-list] ocamlbuild and installed modules and libraries

[Romain Bardou]

Daniel Bünzli a écrit :
> 
> Le 16 nov. 08 à 21:37, Nicolas Pouillard a écrit :
> 
>> I'm a bit uncomfortable with this kind of dynamic or special tags.
>>
>> However the simplest solution to your problem is probably one of those:
>>
>>  1/ ocamlbuild -cflags -I,+xmlm,xmlm.cmx test.native
> 
> You meant,
> 
>> ocamlbuild -cflags -I,+xmlm -lflags -I,+xmlm,xmlm.cmx test.native
> 
> 
> I still think using ocamlbuild with installed libraries/modules is a 
> little bit problematic. If we have to do it that way [1] we are 
> hard-coding the location of the library in the plugin which doesn't feel 
> right.
> 
> For me there should be (1) a way of defining the dependency on a 
> module/library (hopefully without needing a plugin) and (2) a way of 
> defining its location (-I). These two aspects should be decoupled. This 
> makes it easier to drive the installation process in build scripts by 
> using environment variables, i.e. I just need
> to specify the location of the module/library I depend on via a suitable 
> -I $DEPDIR to compile the sources.

Isn't it almost as simple to write, in a script:
   ocamlbuild -cflags -I,$DEPDIR -lflags -I,$DEPDIR
instead of:
   ocamlbuild -I $DEPDIR
Remember that $DEPDIR must be absolute, or relative to the _build directory.

Then you can use ocamlbuild with the -lib option as usual, in a 
"decoupled" way. For instance, if bla/bla.cma is in your current directory:

$ ocamlbuild -classic-display -lib bla -cflags -I,../bla -lflags 
-I,../bla test.byte
ocamldep.opt -modules test.ml > test.ml.depends
ocamlc.opt -c -I ../bla -o test.cmo test.ml
ocamlc.opt -I ../bla bla.cma test.cmo -o test.byte

And for modules, instead of -lib bla, you write -lflags bla.cmo or 
-lflags bla.cmx. You can have several -lflags if you want. Unfortunately 
you have to specify the extension, so it is true that a -mod option 
would actually add something.

I admit, though, that it is not really easy to understand how to include 
a library. One solution would be to have findlib in ocamlbuild, but even 
then, there would be problems if you want a Makefile which is supposed 
to work also when findlib is not installed.

I think there is a recent debate about the -I option of Ocamlbuild...

-- 
Romain Bardou

Re: [Caml-list] ocamlbuild and installed modules and libraries

[Daniel Bünzli]

Le 17 nov. 08 à 10:54, Romain Bardou a écrit :

> Isn't it almost as simple to write, in a script:
>  ocamlbuild -cflags -I,$DEPDIR -lflags -I,$DEPDIR
> instead of:
>  ocamlbuild -I $DEPDIR
> Remember that $DEPDIR must be absolute, or relative to the _build  
> directory.

Yes, I can live with that.

> And for modules, instead of -lib bla, you write -lflags bla.cmo or - 
> lflags bla.cmx. You can have several -lflags if you want.  
> Unfortunately you have to specify the extension, so it is true that  
> a -mod option would actually add something.

That is the point, from my perspective the problem is solved for  
libraries but not for single modules.

Daniel