--- a/hgmerge	Tue Dec 18 14:01:42 2007 -0600
+++ b/hgmerge	Wed Dec 05 20:40:01 2007 +0900
@@ -17,8 +17,12 @@
 BASE="$2"
 OTHER="$3"
 
-if [ -z "$EDITOR" ]; then
-    EDITOR="vi"
+if [ -n "$VISUAL" ]; then
+    EDIT_PROG="$VISUAL"
+elif [ -n "$EDITOR" ]; then
+    EDIT_PROG="$EDITOR"
+else
+    EDIT_PROG="vi"
 fi
 
 # find decent versions of our utilities, insisting on the GNU versions where we
@@ -165,16 +169,16 @@
     fi
 fi
 
-# Attempt to do a merge with $EDITOR
+# Attempt to do a merge with $EDIT_PROG
 if [ -n "$MERGE" -o -n "$DIFF3" ]; then
     echo "conflicts detected in $LOCAL"
     cp "$BACKUP" "$CHGTEST"
-    case "$EDITOR" in
+    case "$EDIT_PROG" in
         "emacs")
-            $EDITOR "$LOCAL" --eval '(condition-case nil (smerge-mode 1) (error nil))' || failure
+            $EDIT_PROG "$LOCAL" --eval '(condition-case nil (smerge-mode 1) (error nil))' || failure
             ;;
         *)
-            $EDITOR "$LOCAL" || failure
+            $EDIT_PROG "$LOCAL" || failure
             ;;
     esac
     # Some editors do not return meaningful error codes
@@ -195,7 +199,7 @@
         success
     else
         # If rejects are empty after using the editor, merge was ok
-        $EDITOR "$LOCAL" "$LOCAL.rej" || failure
+        $EDIT_PROG "$LOCAL" "$LOCAL.rej" || failure
         $TEST -s "$LOCAL.rej" || success
     fi
     failure

--- a/mercurial/commands.py	Tue Dec 18 14:01:42 2007 -0600
+++ b/mercurial/commands.py	Wed Dec 05 20:40:01 2007 +0900
@@ -430,8 +430,8 @@
     If a list of files is omitted, all changes reported by "hg status"
     will be committed.
 
-    If no commit message is specified, the editor configured in your hgrc
-    or in the EDITOR environment variable is started to enter a message.
+    If no commit message is specified, the configured editor is started to
+    enter a message.
     """
     def commitfunc(ui, repo, files, message, match, opts):
         return repo.commit(files, message, opts['user'], opts['date'], match,
@@ -748,9 +748,7 @@
 
     # editor
     ui.status(_("Checking commit editor...\n"))
-    editor = (os.environ.get("HGEDITOR") or
-              ui.config("ui", "editor") or
-              os.environ.get("EDITOR", "vi"))
+    editor = ui.geteditor()
     cmdpath = util.find_exe(editor) or util.find_exe(editor.split()[0])
     if not cmdpath:
         if editor == 'vi':

--- a/mercurial/help.py	Tue Dec 18 14:01:42 2007 -0600
+++ b/mercurial/help.py	Wed Dec 05 20:40:01 2007 +0900
@@ -43,8 +43,7 @@
     'hg' (with com/exe/bat/cmd extension on Windows) is searched.
 
 HGEDITOR::
-    This is the name of the editor to use when committing. Defaults to the
-    value of EDITOR.
+    This is the name of the editor to use when committing. See EDITOR.
 
     (deprecated, use .hgrc)
 
@@ -94,9 +93,16 @@
     If neither HGUSER nor EMAIL is set, LOGNAME will be used (with
     '@hostname' appended) as the author value for a commit.
 
+VISUAL::
+    This is the name of the editor to use when committing. See EDITOR.
+
 EDITOR::
-    This is the name of the editor used in the hgmerge script. It will be
-    used for commit messages if HGEDITOR isn't set. Defaults to 'vi'.
+    Sometimes Mercurial needs to open a text file in an editor for a user
+    to modify, for example when writing commit messages or when using the
+    hgmerge script. The editor it uses is determined by looking at the
+    environment variables HGEDITOR, VISUAL and EDITOR, in that order. The
+    first non-empty one is chosen. If all of them are empty, the editor
+    defaults to 'vi'.
 
 PYTHONPATH::
     This is used by Python to find imported modules and may need to be set

--- a/mercurial/ui.py	Tue Dec 18 14:01:42 2007 -0600
+++ b/mercurial/ui.py	Wed Dec 05 20:40:01 2007 +0900
@@ -440,9 +440,7 @@
             f.write(text)
             f.close()
 
-            editor = (os.environ.get("HGEDITOR") or
-                    self.config("ui", "editor") or
-                    os.environ.get("EDITOR", "vi"))
+            editor = self.geteditor()
 
             util.system("%s \"%s\"" % (editor, name),
                         environ={'HGUSER': user},
@@ -464,3 +462,11 @@
         if self.traceback:
             traceback.print_exc()
         return self.traceback
+
+    def geteditor(self):
+        '''return editor to use'''
+        return (os.environ.get("HGEDITOR") or
+                self.config("ui", "editor") or
+                os.environ.get("VISUAL") or
+                os.environ.get("EDITOR", "vi"))
+