From: Luigi Ballabio <ballabio@...>
Date: 2002-01-16T20:52:10+09:00
Subject: Re: Swig Ruby documentation mods.

At 11:09 AM 1/16/02 +0000, Hugh Sasse Staff Elec Eng wrote:
>On Wed, 16 Jan 2002, Luigi Ballabio wrote:
> > >* if you don't use -module in the swig -ruby command then swig
> > >   complains.  This is probably always correct, but needs mentioning.
> >
> > Are you sure you are including the %module directive in your .i file?
> > I'm not using -module and SWIG doesn't complain.
>
>I'm not using a .i file -- I'm using the fact that swig -ruby example.c
>will generally work, as described elsewhere in the docs.

Oh, I see. Then I agree: SWIG is correct in complaining, but this needs 
mentioning.

> > >* It is not clear what should be done about integrating several C
> > >   functions into the same module.  Does this depend on one writing a .i
> > >   file to connect them together?  How?
> >
> > - I write a file mymodule.i containing:
> >
> > %module MyModule
> > %include somefuncs.i
> > %include someotherfuncs.i
> >
> > - by running SWIG on the latter file, all functions from the two original
> > ones will be exported in MyModule.
>
>Will it produce one "%s_wrap.c" or two?

Just one.

> > If you want to get fancy, you can compare the modification times of
> > MyModule.i and mymodule_wrap.cpp and run swig only when needed
>
>Yes, that sort of thing would work, but since extconf is supposed to be
>used to write a makefile, it seems a bit much to re-implement make
>inside it! :-)

I see your point.
Ok, how about:

require 'mkmf'
require 'ftools'

# create the wrapper file if it doesn't exist yet (i.e., first extconf run)
# since it is needed in order to create a correct makefile
system('swig -ruby MyModule.i') unless File.exists? "mymodule_wrap.cpp"

# create the makefile
create_makefile('MyModule')

# add the target to the makefile
makefile = File.new("Makefile","a")  # open in append mode
makefile << "\n"
makefile << "mymodule_wrap.cpp: MyModule.i\n"
makefile << "\tswig -ruby MyModule.i\n"
makefile.close
# Done. Now the makefile will do the job as expected.

Again, I didn't test the above.

Bye,
         Luigi