Re: mixed language coding

[Jim Edwards <jedwards inmet gov br>]

Paolo Molaro wrote:

> On 06/19/01 Jim Edwards wrote:
>
> > 1.  Write all the gui in c and call the perl code from within callback
> > wrappers written in c.
> >     This seems like it would involve a lot of interface writing.
>
> Uhm, I don't know if this makes sense: if the non-ui part is already
> written in C and you write also the GUI in C, where does perl fit?

There is existing non-ui perl code which is not part of the gui, there is
also a good deal of non-ui c code.


> > 2.  Write the part of the gui for the perl in perl and  the rest in c -
> > I think i would then need many fewer calls from c to perl
> >       possibly only two - one to setup the interface and another to
> > invoke the dialog.
> >
> > Does anyone know of an example that does this and what kind of problems
> > i might encounter?
>
> It depends what kind of graphical interface you need or how complex is the
> interface to the C code. Basically:
>
> 1) if the C interface is complex, just maintain the C program and
> embed a perl interpreter that will be invoked to do the GUI stuff
> (this is the way I did the perl bindings for AbiWord). perlembed
> is the manpage you're looking for to do this.
>
> 2) the C interface is simple: wrap it in an XS module and use that module
> in your GUI program written in perl (you will need the perlxs and perlguts
> manpages for this item). This is a solution that allows for more
> flexibility: it may be worth it even if the C interface is complex
> (for example creating the XS module for the Gtk+ library surely was
> worth it:-).
>
> The first solution may be more simple if you don't know (or don't want
> to know:-) how XS works.

I've got lots of painful experience in XS.  I really was hoping to find
someone who had already tried this.

I think that the route I am considering at this point is as follows:

1. Rewrite the perl/Tk to Gtk-Perl using glade

2.  Write the gtk+ interface to the c in c using glade

3.  Write new XS to call the c interface routines from perl.  I shouldn´t
need more than a few of these calls.

4.  Run the mainloop from perl.

    So my question really is that I intend to assign some callbacks to c code
and others to perl code -  If I stick to assigning callbacks to perl from the
perl side and callbacks to c from the c side, should it be doable or does
someone out there know of a problem I will encounter.  What if I want to
assign a callback to c from the perl side - or one to perl from the c side?
I assume I would need to assign the callback to the same language and write a
wrapper to the other...

Jim