Re: eval

[Dirk Herrmann]

On Thu, 1 Feb 2001, Dirk Herrmann wrote:

> SOLUTION:
> ---------
> 
> Instead of having only one global variable 'the-module', we have
> 'the-module' and 'the-interaction-module'.  Only 'the-module' is restored
> after the execution of 'eval, while 'the-interaction-module' remains
> changed after 'eval has finished.  The value of 'the-interaction-module'
> is reported by (interaction-environment).

A patch that shows how this would look like is below.  It looks more
complicated as it actually is, because I also brought some code pieces into a
more logical order.  Unfortunately I was not able to tell diff to produce an
output as with:

===========
@@ <line info>
code before
-----------
code after
@@ ... next hunk

Hints how to produce such a diff are welcome :-)

Moreover, the patch is quite 'conservative':  it keeps the-module and
the-interaction-module always in sync.  The only exception is in scm_eval.
Probably the-interaction-module would not have to be changed in most of these
places.

Best regards,
Dirk



Index: ice-9/boot-9.scm
===================================================================
RCS file: /cvs/guile/guile-core/ice-9/boot-9.scm,v
retrieving revision 1.223
diff -u -r1.223 boot-9.scm
--- ice-9/boot-9.scm    2001/01/26 16:58:48     1.223
+++ ice-9/boot-9.scm    2001/02/01 16:52:50
@@ -727,7 +727,7 @@
 (read-hash-extend #\' (lambda (c port)
                        (read port)))
 (read-hash-extend #\. (lambda (c port)
-                       (eval (read port) (interaction-environment))))
+                       (eval (read port) (current-environment))))
 
 
 ;;; {Command Line Options}
@@ -1333,9 +1333,11 @@
 ;;
 (define the-module (make-fluid))
 
-;; scm:eval-transformer
+;; current-module
 ;;
-;;(define scm:eval-transformer (make-fluid)) ; initialized in eval.c.
+;; return the current module as viewed by the normalizer.
+;;
+(define (current-module) (fluid-ref the-module))
 
 ;; set-current-module module
 ;;
@@ -1354,27 +1356,47 @@
       (fluid-set! *top-level-lookup-closure* #f)))
 
 
-;; current-module
+;; the-interaction-module
 ;;
-;; return the current module as viewed by the normalizer.
+;; This is the module used for interactive evaluation of code, which is
+;; reported by (interactive-environment).
 ;;
-(define (current-module) (fluid-ref the-module))
+;; NOTE: This binding is used in libguile/modules.c.
+;;
+(define the-interaction-module (make-fluid))
+
+(define (set-interaction-module m)
+  (fluid-set! the-interaction-module m))
+
+
+;; scm:eval-transformer
+;;
+;;(define scm:eval-transformer (make-fluid)) ; initialized in eval.c.
+
 
 ;;; {Module-based Loading}
 ;;;
 
 (define (save-module-excursion thunk)
   (let ((inner-module (current-module))
-       (outer-module #f))
+       (inner-interaction-module (interaction-environment))
+       (outer-module #f)
+       (outer-interaction-module #f))
     (dynamic-wind (lambda ()
                    (set! outer-module (current-module))
+                   (set! outer-interaction-module (interaction-environment))
                    (set-current-module inner-module)
-                   (set! inner-module #f))
+                   (set-interaction-module inner-interaction-module)
+                   (set! inner-module #f)
+                   (set! inner-interaction-module #f))
                  thunk
                  (lambda ()
                    (set! inner-module (current-module))
+                   (set! inner-interaction-module (interaction-environment))
                    (set-current-module outer-module)
-                   (set! outer-module #f)))))
+                   (set-interaction-module outer-interaction-module)
+                   (set! outer-module #f)
+                   (set! outer-interaction-module #f)))))
 
 (define basic-load load)
 
@@ -1547,6 +1569,7 @@
 (for-each set-system-module! (list the-root-module the-scm-module) '(#t #t))
 
 (set-current-module the-root-module)
+(set-interaction-module the-root-module)
 
 (define app (make-module 31))
 (local-define '(app modules) (make-module 31))
@@ -1821,6 +1844,7 @@
                    (save-module-excursion
                     (lambda ()
                       (set-current-module mod)
+                      (set-interaction-module mod)
                       (set-module-public-interface! mod mod)
                       (dynamic-call (cadr modinfo) (caddr modinfo))
                       ))
@@ -2516,8 +2540,10 @@
 (defmacro define-module args
   `(let* ((process-define-module process-define-module)
          (set-current-module set-current-module)
+         (set-interaction-module set-interaction-module)
          (module (process-define-module ',args)))
      (set-current-module module)
+     (set-interaction-module module)
      module))
 
 ;; the guts of the use-modules macro.  add the interfaces of the named
@@ -2573,7 +2599,7 @@
            ;; suggests we use eval here to accomodate Hobbit; it lets
            ;; the interpreter handle the define-private form, which
            ;; Hobbit can't digest.
-           (eval '(define-private ,@ args) (interaction-environment)))))))
+           (eval '(define-private ,@ args) (current-module)))))))
 
 
 
Index: ice-9/emacs.scm
===================================================================
RCS file: /cvs/guile/guile-core/ice-9/emacs.scm,v
retrieving revision 1.22
diff -u -r1.22 emacs.scm
--- ice-9/emacs.scm     2000/12/08 15:39:10     1.22
+++ ice-9/emacs.scm     2001/02/01 16:52:50
@@ -137,7 +137,9 @@
                        (save-module-excursion
                         (lambda ()
                           (if module
-                              (set-current-module (resolve-module module #f)))
+                              (let* ((m (resolve-module module #f)))
+                                (set-current-module m)
+                                (set-interaction-module m)))
                           (let ((result
                                  (start-stack read-and-eval!
                                               (read-and-eval! %%load-port))))
Index: ice-9/slib.scm
===================================================================
RCS file: /cvs/guile/guile-core/ice-9/slib.scm,v
retrieving revision 1.31
diff -u -r1.31 slib.scm
--- ice-9/slib.scm      2000/11/28 13:40:40     1.31
+++ ice-9/slib.scm      2001/02/01 16:52:50
@@ -142,6 +142,7 @@
   (save-module-excursion
    (lambda ()
      (set-current-module slib-module)
+     (set-interaction-module slib-module)
      (let ((errinfo (catch 'system-error
                           (lambda ()
                             (load-from-path name)
Index: libguile/modules.c
===================================================================
RCS file: /cvs/guile/guile-core/libguile/modules.c,v
retrieving revision 1.17
diff -u -r1.17 modules.c
--- libguile/modules.c  2000/12/08 17:32:56     1.17
+++ libguile/modules.c  2001/02/01 16:52:50
@@ -70,6 +70,8 @@
   return SCM_CDR (the_root_module);
 }
 
+
+/* This is the module selected during loading of code.  */
 static SCM the_module;
 
 SCM
@@ -78,12 +80,8 @@
   return scm_fluid_ref (SCM_CDR (the_module));
 }
 
-static SCM set_current_module;
 
-/* This is the module selected during loading of code.  Currently,
- * this is the same as (interaction-environment), but need not be in
- * the future.
- */
+static SCM set_current_module;
 
 SCM
 scm_select_module (SCM module)
@@ -93,6 +91,10 @@
   return old;
 }
 
+
+/* This is the module used for interactive execution of code.  */
+static SCM the_interaction_module;
+
 SCM_DEFINE (scm_interaction_environment, "interaction-environment", 0, 0, 0,
            (),
            "This procedure returns a specifier for the environment that 
contains\n"
@@ -102,10 +104,11 @@
            "dynamically typed by the user.")
 #define FUNC_NAME s_scm_interaction_environment
 {
-  return scm_selected_module ();
+  return scm_fluid_ref (SCM_CDR (the_interaction_module));
 }
 #undef FUNC_NAME
 
+
 SCM_SYMBOL (scm_sym_app, "app");
 SCM_SYMBOL (scm_sym_modules, "modules");
 static SCM module_prefix;
@@ -287,6 +290,7 @@
   the_root_module = scm_intern0 ("the-root-module");
   the_module = scm_intern0 ("the-module");
   set_current_module = scm_intern0 ("set-current-module");
+  the_interaction_module = scm_intern0 ("the-interaction-module");
   module_prefix = scm_permanent_object (SCM_LIST2 (scm_sym_app,
                                                   scm_sym_modules));
   make_modules_in = scm_intern0 ("make-modules-in");