Re: Re[1]: Catching an error

[Alexandre Guillemet <aguillem@ens-lyon.fr>]

> From: "Eric M. Ludlam" <zappo@ultranet.com>
> To: aguillem@ens-lyon.fr
> CC: guile@cygnus.com
> Subject: Re[1]: Catching an error
> Mime-Version: 1.0
> 
> >>> Alexandre Guillemet <aguillem@ens-lyon.fr> seems to think that:
> >Hello
> >
> >I work with the 1.2 version of guile.
> >I don't know to use the function : gh_eval_str_with_catch
> >What is exactly the type  scm_catch_handler_t ?
> >I need to catch the error provide by an syntaxic error in a C string.
> >There's nothing about it in the tutorial and other docs I found.
>   [ ... ]
> 
> If I recall correctly the function gh_eval_str_with_catch does not
> work as advertised (or not advertised in this case) in 1.2.  You can
> get the same behavior with the attached code snippet.  "catcher" is a
> function to run when there is an error.  cs_eval_str is the function
> you call with a C string.
> 
> The output of catcher is my own devising, and isn't as helpful as I'd
> necessarily like.  Also, you don't have to use the stack version of
> the catch routine.  I just happen to like stack traces. :)
> 
> Eric
> 
> ---------
> static SCM catcher(void *data, SCM tag, SCM throw_args)
> {
>   SCM tmp;
>   SCM the_stack;
>   SCM port = scm_current_output_port();  /* set this to whatever */
> 
>   /* Throw args seem to be: ( FN FORMAT ARGS #f )
>    */
>   scm_puts("Function: ", port);
>   scm_display(gh_car(throw_args), port);
>   scm_puts(", ", port);
>   scm_display(tag, port);
>   scm_newline(port);
>   tmp = gh_cadr(throw_args);
>   if(gh_string_p(tmp))
>     {
>       scm_puts("Error: ", port);
>       scm_display_error_message(tmp, gh_caddr(throw_args), port);
>     }
>   scm_puts("Other Data: ", port);
>   scm_display(gh_car(gh_cdddr(throw_args)), port);
>   scm_newline(port);
>   scm_newline(port);
> 
>   the_stack = scm_fluid_ref(SCM_CDR(scm_the_last_stack_fluid));
> 
>   if(SCM_NFALSEP(the_stack))
>     {
>       scm_display_backtrace(the_stack, port, SCM_UNDEFINED, SCM_UNDEFINED);
>     }
> 
>   return gh_int2scm(1);
> }
> 
> void cs_eval_str(char *str)
> {
>   scm_internal_stack_catch (SCM_BOOL_T, (scm_catch_body_t) gh_eval_str, str,
> 			    (scm_catch_handler_t) catcher, str);
> }


Thanks for your help, it works fine ;)

Alexandre Guillemet