Re: Using guile as an extension language for GNU make

[Paul Smith <psmith@gnu.org>]

On Sun, 2011-09-18 at 17:30 +0200, Thien-Thi Nguyen wrote:
> The double-quote stripping is kind of hacky.  I would create a port
> and ‘display’ the result of ‘scm_c_eval_string’ to it.

Thanks for the hints.  I've reworked my code to implement a generic "SCM
to make string" function; currently it looks like this:

        char *
        cvt_scm_to_str (SCM obj)
        {
          char *str;
        
          if (scm_is_bool (obj) && scm_is_true (obj))
            str = xstrdup ("t");
          else if (scm_is_number (obj) || scm_is_string (obj) || scm_is_symbol (obj))
            {
              SCM port = scm_open_output_string ();
        
              scm_display (obj, port);
              str = scm_to_locale_string (scm_get_output_string (port));
              scm_close_output_port (port);
            }
          else
            str = xstrdup ("");
        
          return str;
        }

That's better than what I had before, but I still have some concerns.
For example, what if a Guile call wanted to return a list?  I can use
display as above, but the list will be enclosed in parentheses, which is
not how make displays lists.  Is there a clean way to handle this?  I
could write a function then invoke it with scm_map() (right?) but this
seems like it might be work.  Also what if the data structure is more
complex, where some elements of the list are lists themselves, etc.?  I
can "flatten" the entire thing out, I suppose.

Or I could ignore them as above and require the Guile scripting to
convert the list into a string before returning it.

-- 
-------------------------------------------------------------------------------
 Paul D. Smith <psmith@gnu.org>          Find some GNU make tips at:
 http://www.gnu.org                      http://make.mad-scientist.net
 "Please remain calm...I may be mad, but I am a professional." --Mad Scientist