[Emacs-diffs] master 599ca62: `save-excursion' does not save&restore the mark any more

[Stefan Monnier]

branch: master
commit 599ca626d760215b090012c69c749d391cfd6fbe
Author: Stefan Monnier <address@hidden>
Commit: Stefan Monnier <address@hidden>

    `save-excursion' does not save&restore the mark any more
    
    * src/editfns.c (save_excursion_save): Don't save the mark.
    (save_excursion_restore): Don't restore the mark.
    (Fsave_excursion): Fix docstring accordingly.
    
    * doc/lispintro/emacs-lisp-intro.texi:
    * doc/lispref/positions.texi (Excursions, Narrowing): `save-excursion' does
    not save&restore the mark any more.
---
 doc/lispintro/ChangeLog             |    4 ++
 doc/lispintro/emacs-lisp-intro.texi |   44 ++++++++++++++--------------
 doc/lispref/ChangeLog               |    5 +++
 doc/lispref/positions.texi          |   21 +++++--------
 etc/NEWS                            |    2 +
 src/ChangeLog                       |    6 ++++
 src/editfns.c                       |   54 +++++-----------------------------
 7 files changed, 55 insertions(+), 81 deletions(-)

diff --git a/doc/lispintro/ChangeLog b/doc/lispintro/ChangeLog
index 57ab03b..c54c165 100644
--- a/doc/lispintro/ChangeLog
+++ b/doc/lispintro/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-25  Stefan Monnier  <address@hidden>
+
+       * emacs-lisp-intro.texi: `save-excursion' doesn't save&restore the mark.
+
 2014-12-31  Paul Eggert  <address@hidden>
 
        Less 'make' chatter for Emacs doc
diff --git a/doc/lispintro/emacs-lisp-intro.texi 
b/doc/lispintro/emacs-lisp-intro.texi
index c67623d..ed125bb 100644
--- a/doc/lispintro/emacs-lisp-intro.texi
+++ b/doc/lispintro/emacs-lisp-intro.texi
@@ -352,7 +352,7 @@ How To Write Function Definitions
 * if::                           What if?
 * else::                         If--then--else expressions.
 * Truth & Falsehood::            What Lisp considers false and true.
-* save-excursion::               Keeping track of point, mark, and buffer.
+* save-excursion::               Keeping track of point and buffer.
 * Review::
 * defun Exercises::
 
@@ -2966,7 +2966,7 @@ symbol refers to it.)
 * if::                           What if?
 * else::                         If--then--else expressions.
 * Truth & Falsehood::            What Lisp considers false and true.
-* save-excursion::               Keeping track of point, mark, and buffer.
+* save-excursion::               Keeping track of point and buffer.
 * Review::
 * defun Exercises::
 @end menu
@@ -4159,11 +4159,11 @@ The @code{save-excursion} function is the third and 
final special form
 that we will discuss in this chapter.
 
 In Emacs Lisp programs used for editing, the @code{save-excursion}
-function is very common.  It saves the location of point and mark,
-executes the body of the function, and then restores point and mark to
-their previous positions if their locations were changed.  Its primary
+function is very common.  It saves the location of point,
+executes the body of the function, and then restores point to
+its previous position if its location was changed.  Its primary
 purpose is to keep the user from being surprised and disturbed by
-unexpected movement of point or mark.
+unexpected movement of point.
 
 @menu
 * Point and mark::              A review of various locations.
@@ -4201,7 +4201,7 @@ region}.  Numerous commands work on the region, including
 @code{print-region}.
 
 The @code{save-excursion} special form saves the locations of point and
-mark and restores those positions after the code within the body of the
+restores this position after the code within the body of the
 special form is evaluated by the Lisp interpreter.  Thus, if point were
 in the beginning of a piece of text and some code moved point to the end
 of the buffer, the @code{save-excursion} would put point back to where
@@ -4212,16 +4212,16 @@ In Emacs, a function frequently moves point as part of 
its internal
 workings even though a user would not expect this.  For example,
 @code{count-lines-region} moves point.  To prevent the user from being
 bothered by jumps that are both unexpected and (from the user's point of
-view) unnecessary, @code{save-excursion} is often used to keep point and
-mark in the location expected by the user.  The use of
+view) unnecessary, @code{save-excursion} is often used to keep point in
+the location expected by the user.  The use of
 @code{save-excursion} is good housekeeping.
 
 To make sure the house stays clean, @code{save-excursion} restores the
-values of point and mark even if something goes wrong in the code inside
+value of point even if something goes wrong in the code inside
 of it (or, to be more precise and to use the proper jargon, ``in case of
 abnormal exit'').  This feature is very helpful.
 
-In addition to recording the values of point and mark,
+In addition to recording the value of point,
 @code{save-excursion} keeps track of the current buffer, and restores
 it, too.  This means you can write code that will change the buffer and
 have @code{save-excursion} switch you back to the original buffer.
@@ -4386,9 +4386,9 @@ For example,
 @end smallexample
 
 @item save-excursion
-Record the values of point and mark and the current buffer before
-evaluating the body of this special form.  Restore the values of point
-and mark and buffer afterward.
+Record the values of point and the current buffer before
+evaluating the body of this special form.  Restore the value of point and
+buffer afterward.
 
 @need 1250
 For example,
@@ -5201,8 +5201,8 @@ of the two-element list, @code{(oldbuf (current-buffer))}.
 The body of the @code{let} expression in @code{append-to-buffer}
 consists of a @code{save-excursion} expression.
 
-The @code{save-excursion} function saves the locations of point and
-mark, and restores them to those positions after the expressions in the
+The @code{save-excursion} function saves the location of point, and restores it
+to that position after the expressions in the
 body of the @code{save-excursion} complete execution.  In addition,
 @code{save-excursion} keeps track of the original buffer, and
 restores it.  This is how @code{save-excursion} is used in
@@ -5390,7 +5390,7 @@ Conventionally bound to @kbd{M-.} (that's a period 
following the
 @key{META} key).
 
 @item save-excursion
-Save the location of point and mark and restore their values after the
+Save the location of point and restore its value after the
 arguments to @code{save-excursion} have been evaluated.  Also, remember
 the current buffer and return to it.
 
@@ -5896,7 +5896,7 @@ the value of point, which will be at the end of the 
inserted text, is
 recorded in the variable @code{newmark}.
 
 After the body of the outer @code{save-excursion} is evaluated, point
-and mark are relocated to their original places.
+is relocated to its original place.
 
 However, it is convenient to locate a mark at the end of the newly
 inserted text and locate point at its beginning.  The @code{newmark}
@@ -6685,8 +6685,8 @@ restored just before the completion of the function by the
 @code{save-restriction} special form.
 
 The call to @code{widen} is followed by @code{save-excursion}, which
-saves the location of the cursor (i.e., of point) and of the mark, and
-restores them after the code in the body of the @code{save-excursion}
+saves the location of the cursor (i.e., of point), and
+restores it after the code in the body of the @code{save-excursion}
 uses the @code{beginning-of-line} function to move point.
 
 (Note that the @code{(widen)} expression comes between the
@@ -6757,8 +6757,8 @@ it, and @code{count-lines} counts only the lines 
@emph{before} the
 current line.
 
 After @code{count-lines} has done its job, and the message has been
-printed in the echo area, the @code{save-excursion} restores point and
-mark to their original positions; and @code{save-restriction} restores
+printed in the echo area, the @code{save-excursion} restores point to
+its original position; and @code{save-restriction} restores
 the original narrowing, if any.
 
 @node narrow Exercise
diff --git a/doc/lispref/ChangeLog b/doc/lispref/ChangeLog
index 9b1bbb3..9e1b7b0 100644
--- a/doc/lispref/ChangeLog
+++ b/doc/lispref/ChangeLog
@@ -1,3 +1,8 @@
+2015-03-25  Stefan Monnier  <address@hidden>
+
+       * positions.texi (Excursions, Narrowing): `save-excursion' does not
+       save&restore the mark any more.
+
 2015-03-24  Paul Eggert  <address@hidden>
 
        * numbers.texi (Float Basics): Improve ldexp documentation.
diff --git a/doc/lispref/positions.texi b/doc/lispref/positions.texi
index b74116e..103161c 100644
--- a/doc/lispref/positions.texi
+++ b/doc/lispref/positions.texi
@@ -825,8 +825,8 @@ is zero or less.
   It is often useful to move point ``temporarily'' within a localized
 portion of the program.  This is called an @dfn{excursion}, and it is
 done with the @code{save-excursion} special form.  This construct
-remembers the initial identity of the current buffer, and its values
-of point and the mark, and restores them after the excursion
+remembers the initial identity of the current buffer, and its value
+of point, and restores them after the excursion
 completes.  It is the standard way to move point within one part of a
 program and avoid affecting the rest of the program, and is used
 thousands of times in the Lisp sources of Emacs.
@@ -841,18 +841,18 @@ Configurations} and in @ref{Frame Configurations}. @c 
frameset?
 @cindex mark excursion
 @cindex point excursion
 This special form saves the identity of the current buffer and the
-values of point and the mark in it, evaluates @var{body}, and finally
-restores the buffer and its saved values of point and the mark.  All
-three saved values are restored even in case of an abnormal exit via
+value of point in it, evaluates @var{body}, and finally
+restores the buffer and its saved value of point.  both saved values are
+restored even in case of an abnormal exit via
 @code{throw} or error (@pxref{Nonlocal Exits}).
 
 The value returned by @code{save-excursion} is the result of the last
 form in @var{body}, or @code{nil} if no body forms were given.
 @end defspec
 
-  Because @code{save-excursion} only saves point and mark for the
+  Because @code{save-excursion} only saves point for the
 buffer that was current at the start of the excursion, any changes
-made to point and/or mark in other buffers, during the excursion, will
+made to point in other buffers, during the excursion, will
 remain in effect afterward.  This frequently leads to unintended
 consequences, so the byte compiler warns if you call @code{set-buffer}
 during an excursion:
@@ -888,11 +888,6 @@ type @code{nil}.  @xref{Marker Insertion Types}.  
Therefore, when the
 saved point value is restored, it normally comes before the inserted
 text.
 
-  Although @code{save-excursion} saves the location of the mark, it does
-not prevent functions which modify the buffer from setting
address@hidden, and thus causing the deactivation of the mark
-after the command finishes.  @xref{The Mark}.
-
 @node Narrowing
 @section Narrowing
 @cindex narrowing
@@ -980,7 +975,7 @@ restores the restrictions on the original buffer (the 
buffer whose
 restrictions it saved from), but it does not restore the identity of the
 current buffer.
 
address@hidden does @emph{not} restore point and the mark; use
address@hidden does @emph{not} restore point; use
 @code{save-excursion} for that.  If you use both @code{save-restriction}
 and @code{save-excursion} together, @code{save-excursion} should come
 first (on the outside).  Otherwise, the old point value would be
diff --git a/etc/NEWS b/etc/NEWS
index 45d5ab3..396335e 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -617,6 +617,8 @@ a typographically-correct documents.
 
 * Incompatible Lisp Changes in Emacs 25.1
 
+** `save-excursion' does not save&restore the mark any more.
+
 ** read-buffer-function can now be called with a 4th argument (`predicate').
 
 ** completion-table-dynamic stays in the minibuffer.
diff --git a/src/ChangeLog b/src/ChangeLog
index 23f125c..632b798 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2015-03-25  Stefan Monnier  <address@hidden>
+
+       * editfns.c (save_excursion_save): Don't save the mark.
+       (save_excursion_restore): Don't restore the mark.
+       (Fsave_excursion): Fix docstring accordingly.
+
 2015-03-24  Paul Eggert  <address@hidden>
 
        Fix minor ldexp issues
diff --git a/src/editfns.c b/src/editfns.c
index 7c146f1..f463890 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -849,14 +849,11 @@ save_excursion_save (void)
 {
   return make_save_obj_obj_obj_obj
     (Fpoint_marker (),
-     /* Do not copy the mark if it points to nowhere.  */
-     (XMARKER (BVAR (current_buffer, mark))->buffer
-      ? Fcopy_marker (BVAR (current_buffer, mark), Qnil)
-      : Qnil),
+     Qnil,
      /* Selected window if current buffer is shown in it, nil otherwise.  */
      (EQ (XWINDOW (selected_window)->contents, Fcurrent_buffer ())
       ? selected_window : Qnil),
-     BVAR (current_buffer, mark_active));
+     Qnil);
 }
 
 /* Restore saved buffer before leaving `save-excursion' special form.  */
@@ -864,8 +861,8 @@ save_excursion_save (void)
 void
 save_excursion_restore (Lisp_Object info)
 {
-  Lisp_Object tem, tem1, omark, nmark;
-  struct gcpro gcpro1, gcpro2, gcpro3;
+  Lisp_Object tem, tem1;
+  struct gcpro gcpro1;
 
   tem = Fmarker_buffer (XSAVE_OBJECT (info, 0));
   /* If we're unwinding to top level, saved buffer may be deleted.  This
@@ -873,8 +870,7 @@ save_excursion_restore (Lisp_Object info)
   if (NILP (tem))
     goto out;
 
-  omark = nmark = Qnil;
-  GCPRO3 (info, omark, nmark);
+  GCPRO1 (info);
 
   Fset_buffer (tem);
 
@@ -883,34 +879,6 @@ save_excursion_restore (Lisp_Object info)
   Fgoto_char (tem);
   unchain_marker (XMARKER (tem));
 
-  /* Mark marker.  */
-  tem = XSAVE_OBJECT (info, 1);
-  omark = Fmarker_position (BVAR (current_buffer, mark));
-  if (NILP (tem))
-    unchain_marker (XMARKER (BVAR (current_buffer, mark)));
-  else
-    {
-      Fset_marker (BVAR (current_buffer, mark), tem, Fcurrent_buffer ());
-      nmark = Fmarker_position (tem);
-      unchain_marker (XMARKER (tem));
-    }
-
-  /* Mark active.  */
-  tem = XSAVE_OBJECT (info, 3);
-  tem1 = BVAR (current_buffer, mark_active);
-  bset_mark_active (current_buffer, tem);
-
-  /* If mark is active now, and either was not active
-     or was at a different place, run the activate hook.  */
-  if (! NILP (tem))
-    {
-      if (! EQ (omark, nmark))
-       run_hook (intern ("activate-mark-hook"));
-    }
-  /* If mark has ceased to be active, run deactivate hook.  */
-  else if (! NILP (tem1))
-    run_hook (intern ("deactivate-mark-hook"));
-
   /* If buffer was visible in a window, and a different window was
      selected, and the old selected window is still showing this
      buffer, restore point in that window.  */
@@ -932,18 +900,12 @@ save_excursion_restore (Lisp_Object info)
 }
 
 DEFUN ("save-excursion", Fsave_excursion, Ssave_excursion, 0, UNEVALLED, 0,
-       doc: /* Save point, mark, and current buffer; execute BODY; restore 
those things.
+       doc: /* Save point, and current buffer; execute BODY; restore those 
things.
 Executes BODY just like `progn'.
-The values of point, mark and the current buffer are restored
+The values of point and the current buffer are restored
 even in case of abnormal exit (throw or error).
-The state of activation of the mark is also restored.
-
-This construct does not save `deactivate-mark', and therefore
-functions that change the buffer will still cause deactivation
-of the mark at the end of the command.  To prevent that, bind
-`deactivate-mark' with `let'.
 
-If you only want to save the current buffer but not point nor mark,
+If you only want to save the current buffer but not point,
 then just use `save-current-buffer', or even `with-current-buffer'.
 
 usage: (save-excursion &rest BODY)  */)