Re: exporting first class global variables from c...

[Matthias Koeppe]

Matthew Whitworth <address@hidden> writes:

> I've just started experimenting with Guile (and Scheme for that matter)
> and have worked through and the tortoise tutorial.  Now I would like
> to export global variable from my C program into Guile where it can be
> modified by set!, but I can't figure out how to do it or find any
> documentation.
>
> SWIG seems to accomplish this by wrapping the C variable in a dual-purpose
> getter/setter function, but the semantics seem a liitle kludgy (and
> I've had some trouble getting things to work as I expected).

If you invoke recent SWIG versions (1.3.x) with the "-emit-setters"
option, SWIG creates "procedures-with-setters" for C variables.  This
means that you can use the syntax (VARIABLE) to get the value and
(set! (VARIABLE) VALUE) to set it.

If you don't use SWIG, you can accomplish the same using the
scm_make_procedure_with_setter() C function.

Regards,

-- 
Matthias Köppe -- http://www.math.uni-magdeburg.de/~mkoeppe