Make goto-char offer the number at point as default

* lisp/subr.el (read-natnum-interactive): New function to read natural
numbers for interactive functions.
* src/editfns.c (Fgoto_char): Call read-natnum-interactive from the
interactive definition of goto-char to offer the number at point as
default.  Also expand the docstring to document this new interactive
behavior.
* doc/emacs/basic.texi (Moving Point): Expand the Emacs manual to
document this new behavior.
* etc/NEWS: And announce it (bug#45199).

diff --git a/doc/emacs/basic.texi b/doc/emacs/basic.texi
index cd1ffbebd7c934ce19d518d5b4d7169d925e0397..77c80547462c6f6acdefbecf35c42d2383e335c8 100644 (file)
--- a/doc/emacs/basic.texi
+++ b/doc/emacs/basic.texi
@@ -310,7 +310,10 @@ Scroll one screen backward, and move point onscreen if necessary
 @kindex M-g c
 @findex goto-char
 Read a number @var{n} and move point to buffer position @var{n}.
-Position 1 is the beginning of the buffer.
+Position 1 is the beginning of the buffer.  If point is on or just
+after a number in the buffer, that is the default for @var{n}.  Just
+type @key{RET} in the minibuffer to use it.  You can also specify
+@var{n} by giving @kbd{M-g c} a numeric prefix argument.
 
 @item M-g M-g
 @itemx M-g g

diff --git a/etc/NEWS b/etc/NEWS
index a5e2c9cf26aede40b2757834c95927d827f71a90..05274a2d6c60bb7ea4399879aa3a596dfb913da1 100644 (file)
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -257,6 +257,10 @@ When 'widen-automatically' is non-nil, 'goto-line' widens the narrowed
 buffer to be able to move point to the inaccessible portion.
 'goto-line-relative' is bound to 'C-x n g'.
 
++++
+** When called interactively, 'goto-char' now offers the number at
+point as default.
+
 +++
 ** When 'suggest-key-bindings' is non-nil, the completion list of 'M-x'
 shows equivalent key bindings for all commands that have them.

diff --git a/lisp/subr.el b/lisp/subr.el
index ed235ee1f7295d2cb8f57871d19351423828922d..77c19c5bbf35b460c0429af2117a27d0a13268ac 100644 (file)
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -2820,6 +2820,15 @@ There is no need to explicitly add `help-char' to CHARS;
     (message "%s%s" prompt (char-to-string char))
     char))
 
+(defun goto-char--read-natnum-interactive (prompt)
+  "Get a natural number argument, optionally prompting with PROMPT.
+If there is a natural number at point, use it as default."
+  (if (and current-prefix-arg (not (consp current-prefix-arg)))
+      (list (prefix-numeric-value current-prefix-arg))
+    (let* ((number (number-at-point))
+           (default (and (natnump number) number)))
+      (list (read-number prompt default)))))
+
 \f
 ;; Behind display-popup-menus-p test.
 (declare-function x-popup-dialog "menu.c" (position contents &optional header))

diff --git a/src/editfns.c b/src/editfns.c
index 4104edd77fd273d263385e86ca0732d8c508968a..e4c4141ef5e00c95bc55b602825a4c2dd1f8b7e7 100644 (file)
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -188,11 +188,16 @@ DEFUN ("point-marker", Fpoint_marker, Spoint_marker, 0, 0, 0,
   return build_marker (current_buffer, PT, PT_BYTE);
 }
 
-DEFUN ("goto-char", Fgoto_char, Sgoto_char, 1, 1, "NGoto char: ",
+DEFUN ("goto-char", Fgoto_char, Sgoto_char, 1, 1,
+         "(goto-char--read-natnum-interactive \"Go to char: \")",
        doc: /* Set point to POSITION, a number or marker.
 Beginning of buffer is position (point-min), end is (point-max).
 
-The return value is POSITION.  */)
+The return value is POSITION.
+
+If called interactively, a numeric prefix argument specifies
+POSITION; without a numeric prefix argument, read POSITION from the
+minibuffer.  The default value is the number at point (if any).  */)
   (register Lisp_Object position)
 {
   if (MARKERP (position))