Suggestion for multiple repl sessions.

[Dirk Herrmann <dirk@ida.ing.tu-bs.de>]

Hello schemers.

Currently guile has problems with initialization. If, for example, I want to
execute scheme code before the repl was called for the first time, I have to
load boot-9 manually. Later, when I enter the repl, guile exits with a stack
overflow because boot-9 is executed for the second time. The same happens
when the repl is to be entered more than once.

I suggest to rename ice-9/boot.scm to ice-9/boot-9-tail.scm and have a new
file ice-9/boot-9.scm which just contains the following lines: 

------------------------------ cut here -------------------------
[standard copyright header]

;;; This file is the first thing loaded into Guile.  If not done before, it
;;; loads boot-9-tail.scm, which adds many mundane definitions and a few that
;;; are interesting. 
;;;
;;; The module system (hence the hierarchical namespace) are also defined in
;;; boot-9-tail.scm file.
;;

(if (not (defined? 'provide))
    (primitive-load-path "ice-9/boot-9-tail.scm"))
------------------------------ cut here -------------------------


This allows to have boot-9 loaded by initialization files and enter a repl 
later.

I also have patched guile to be able to leave and re-enter the repl. The
patches are agains 19980505 snapshot, but apply also to 19980629, hopefully
also to newer snapshots.

The basic change is that scm_shell does not call exit any more but returns an
integer exit status. Thus gh_repl and other caller functions can decide
whether to exit or not. I decided to let gh_repl return the exit status.

The only problem that currently remains for me is, that when you leave the
guile repl by pressing ctrl-d, you cannot re-enter: The ctrl-d character seems
to remain in guile's input buffer and results in an immediate exit. If you
leave guile with (exit) instead, everything is fine.

Best regards, 
Dirk Herrmann



*** ../../guile/libguile/gh_init.c	Tue Nov 25 18:20:21 1997
--- ./gh_init.c	Tue May  5 16:16:55 1998
***************
*** 74,84 ****
  
  /* offer a REPL to the C programmer; for now I just invoke the ice-9
     REPL that is written in Scheme */
! void 
  gh_repl (int argc, char *argv[])
  {
  /*   gh_eval_str ("(top-repl)"); */
!   scm_shell (argc, argv);
  }
  
  /* libguile programmers need exception handling mechanisms; here is
--- 74,84 ----
  
  /* offer a REPL to the C programmer; for now I just invoke the ice-9
     REPL that is written in Scheme */
! int 
  gh_repl (int argc, char *argv[])
  {
  /*   gh_eval_str ("(top-repl)"); */
!   return scm_shell (argc, argv);
  }
  
  /* libguile programmers need exception handling mechanisms; here is
*** ../../guile-core-19980505/libguile/script.c	Sat Apr 18 23:58:47 1998
--- ./script.c	Tue May  5 16:18:05 1998
***************
*** 648,654 ****
  }
  
  
! void
  scm_shell (argc, argv)
       int argc;
       char **argv;
--- 648,654 ----
  }
  
  
! int
  scm_shell (argc, argv)
       int argc;
       char **argv;
***************
*** 666,672 ****
        }
    }
  
!   exit (scm_exit_status (scm_eval_x (scm_compile_shell_switches (argc,argv))));
  }
  
  
--- 666,672 ----
        }
    }
  
!   return scm_exit_status (scm_eval_x (scm_compile_shell_switches (argc,argv)));
  }
  
  
*** ../../guile-core-19980505/libguile/guile.c	Tue May 27 00:32:46 1997
--- ./guile.c	Tue May  5 16:17:16 1998
***************
*** 57,63 ****
  inner_main (void *closure, int argc, char **argv)
  {
    /* module initializations would go here */
!   scm_shell (argc, argv);
  }
  
  int
--- 57,63 ----
  inner_main (void *closure, int argc, char **argv)
  {
    /* module initializations would go here */
!   exit (scm_shell (argc, argv));
  }
  
  int
*** ../../guile-core-19980505/libguile/gh_test_repl.c	Tue Nov 25 18:20:23 1997
--- ./gh_test_repl.c	Tue May  5 16:24:15 1998
***************
*** 101,107 ****
  	  gh_procedure_p (cf), gh_vector_p (cf));
    gh_eval_str("(c-vector-test 200)");
  
!   gh_repl (argc, argv);
  }
  
  int 
--- 101,107 ----
  	  gh_procedure_p (cf), gh_vector_p (cf));
    gh_eval_str("(c-vector-test 200)");
  
!   exit (gh_repl (argc, argv));
  }
  
  int 
*** ../../guile-core-19980505/libguile/script.h	Tue May 27 00:33:48 1997
--- ./script.h	Tue May  5 16:18:28 1998
***************
*** 55,61 ****
  extern int scm_count_argv SCM_P ((char **argv));
  extern void scm_shell_usage SCM_P ((int fatal, char *message));
  extern SCM scm_compile_shell_switches SCM_P ((int argc, char **argv));
! extern void scm_shell SCM_P ((int argc, char **argv));
  extern char *scm_usage_name;
  extern void scm_init_script ();
  
--- 55,61 ----
  extern int scm_count_argv SCM_P ((char **argv));
  extern void scm_shell_usage SCM_P ((int fatal, char *message));
  extern SCM scm_compile_shell_switches SCM_P ((int argc, char **argv));
! extern int scm_shell SCM_P ((int argc, char **argv));
  extern char *scm_usage_name;
  extern void scm_init_script ();
  
*** ../../guile-core-19980505/libguile/gh.h	Sun Mar  1 08:25:59 1998
--- ./gh.h	Tue May  5 16:23:38 1998
***************
*** 61,67 ****
  #endif /* __GNUC__ */
  
  void gh_enter(int argc, char *argv[], void (*c_main_prog)());
! void gh_repl(int argc, char *argv[]);
  SCM gh_catch(SCM tag, scm_catch_body_t body, void *body_data,
  	     scm_catch_handler_t handler, void *handler_data);
  
--- 61,67 ----
  #endif /* __GNUC__ */
  
  void gh_enter(int argc, char *argv[], void (*c_main_prog)());
! int gh_repl(int argc, char *argv[]);
  SCM gh_catch(SCM tag, scm_catch_body_t body, void *body_data,
  	     scm_catch_handler_t handler, void *handler_data);