Re: [slang-users] USIng the LIST inside of C ...

["John E. Davis" <davis@xxxxxxxxxxxxx>]

Ben Duncan <linux4ms@xxxxxxx> wrote:
>I would like to USE the LIST functions:
>such as :
>
>  list = { "hello", 7, 3.14, {&sin, &cos}}
>
>   then
>
>  list_insert (list, 0, "hi");
>  list_append (list, 0, "there");
>  list_insert (list, -1, "before");
>  list_append (list, -1, "after");
>
>inside of my C SLAG programs, then return the created LIST
>back to the S-Lang program.
>
>Any Pointers on how to go about doing this ?

I have not yet created an API to access the slang interpreter list
functions from C.  Until then, you can should be able to call the
interpreter from C and have it create the list for you.  Consider this
slang function:

   define _create_list ()
   {
      variable args = __pop_args (_NARGS);
      return { __push_args (args) };
   }

This can be used from the slang interpreter via, e.g.,

   list = _create_list ("hello", 7, 3.14);

Moreover, you can call this from C (error checking has been omitted
for clarity):

    (void) SLang_start_arg_list ();
    (void) SLang_push_string ("hello");
    (void) SLang_push_int (7);
    (void) SLang_push_double (3.14);
    (void) SLang_end_arg_list ();
    (void) SLang_execute_function ("_create_list");

This will create the list and leave it on the slang stack.

You will have to use a similar approach if you want to manipulate the
list from C.

--John