Re: dbus introspection

[Neil Jerram]

On 2014-04-28 13:49, Max wrote:
> 27.04.2014 15:33, Neil Jerram пишет:
> > I have some FFI-based client-side bindings in my library at
> > http://git.savannah.gnu.org/cgit/ossaulib.git/.  The (glib dbus) 
> > module
> > exports procedures for
> >  - making a synchronous or asynchronous dbus call
> >  - registering a Scheme procedure to be called when a dbus signal
> >    occurs.
> >
> > (ofono modem) is a library module that uses those dbus- procedures, 
> > and
> > I hope is simple enough to make the usage clear.
>
> Excellent. Looks pretty clear to me. I'll just have to go through some
> basic guile
> docs on using external libraries.
> Could you point me to appropriate documentation? I'm kinda lost with 
> differences
> between module, library and R6RS-library.

"library" and "R6RS-library" are R6RS/R7RS terminology.  My code is 
written with Guile's traditional module syntax, so (use-module ...) is 
the right way to use it.  (Sorry for saying "library module" above - I 
can see now that that's confusing.)

http://www.gnu.org/software/guile/manual/html_node/Using-Guile-Modules.html#Using-Guile-Modules 
has general doc in this area.

> In ofono-modem it's simply used as (use-module (glib dbus)) - does it
> mean that I
> have to copy it to some standard location?
> What's there procedure to "install" library so it becomes visible to
> guile-gnome-2?
> Is there way to make your library available to particular user instead
> of system-wide
> availability?
>
> I've tried to set GUILE_LOAD_PATH to ~/source/ossaulib but no luck so 
> far.

For Guile in general I believe that should work; of course you also need 
"export GUILE_LOAD_PATH".

Don't know about guile-gnome-2, though - possibly guile-gnome-2 is also 
setting GUILE_LOAD_PATH and so overriding your setting.

If you have a top level script, you could instead write

 (set! %load-path (append %load-path '("~/source/ossaulib")))

before any (use-module ...) forms.  You might also need to expand the 
"~", as I don't think Guile does that automatically.


> > > Tried to search but found some ancient code only :(
> > What was that?
>
> https://code.launchpad.net/~andywingo/guile-gnome/dbus - this one.
>
> > I know that guile-gnome used to have a dbus module, and possibly still
> > does.
>
> Could you share some links? I've found nothing so far unfortunately.

Same here; my knowledge dates back to the same time as that launchpad 
link - when guile-gnome was managed in a bzr repository.


> Also, if dbus bindings already available via guile-gnome - why develop
> another library?

Thanks for raising this.  It's because the build/deployment process 
becomes massively simpler, especially on embedded devices.

I worked with guile-gnome, some years ago, for my Nokia 770 and N800 
devices.  Unfortunately even core Guile wasn't pre-built in the (armel) 
repositories for those devices, so I had myself to build Guile, then 
slib, then g-wrap, and then guile-gnome, all using a tricky 
scratchbox-based build and package installation process; then copy and 
install all the packages on the devices themselves.  (It took a long 
time too.)

Now I'm working on my GTA04 phone (armhf).  Happily the latest stable 
Guile is pre-built by Debian for armhf, as are the gio/glib/gdbus 
libraries.  So with an FFI approach all I need is to "aptitude install" 
the right -dev packages, then write and deploy some Guile Scheme code.  
I find that much simpler.



> > > Also is there some tool similar to vala-dbus-binding-tool which could 
> > > connect to a
> > > given dbus service and using introspection generate guile stub code 
> > > for
> > > functions/signals available for interaction with this service?
> > Not that I know of.  Should be quite easy to build on top of my
> > client-side bindings, though.  (Or on top of any set of client-side
> > bindings.)
>
> Yepp, I've just hoped someone already made it :)
> Can't really imagine how to use dbus without such a convenience tool.

Can you sketch how you'd want your Scheme code to end up looking?  
"(dbus-call INTERFACE METHOD . PARMS)" is already fairly simple, and I 
think it would be easy to make INTERFACE applicable to get "(INTERFACE 
METHOD . PARMS)".  What do you have in mind?

Regards,
     Neil