Re: Environments, modules, ....

[Chris Cramer]

On Thu, Sep 06, 2001 at 03:05:51PM +0200, Frederick Ros wrote:
> In a C program, I'd like to iterate through the list of all known symbol
> in the current environment.

This is a little difficult in C, but see below.

> Looking at the libguile code, I've been able to find that an
> scm_c_environment_fold function was available, that allow me to apply a
> function to each of the symbol bound in the given environment....
> 
> The problem is how to get this environment ....
> 
> I found some macros (SCM_ENV), or functions (scm_top_level_env), but the
> SCM they return seems to not fit (scm_c_environment_fold complains that
> this is not an environment..)

Unless I'm mistaken, the code in environments.c isn't actually in use yet.
So, I think what you really want to do is search the current module.

> My question is : Can someone provide me with a very short code example,
> or with some pointers in order to be able to get the current
> environment, and to print each of the bound symbol...

(module-search
    (lambda (module v)
        (module-for-each
            (lambda (sym var)
                (display sym)
                (newline))
            module)
        #f)
    (current-module)
    #t)

In C, I suppose you could do something like:

void
list_symbols(SCM module, SCM outp)
{
        SCM     obarray;
        int     i, len;
        SCM     x;

        obarray = SCM_MODULE_OBARRAY(module);
        len = SCM_VECTOR_LENGTH(obarray);
        for (i = 0; i < len; i++) {
                for (x = SCM_VELTS(obarray)[i]; !SCM_NULLP(x); x = SCM_CDR(x))
                        scm_display(SCM_CAR(x), outp);
        }
        x = SCM_MODULE_USES(module);
        for (x = SCM_MODULE_USES(module); !SCM_NULLP(x); x = SCM_CDR(x))
                list_symbols(SCM_CAR(x), outp);
}

and then do list_symbols(scm_current_module(), scm_current_output_port()).

It seems like there should be an easier way, but I couldn't find it.

-- 
C. Ray C. aka Christopher Cramer
address@hidden
http://www.pyro.net/~crayc/