add -i, send-email, svn, p4, etc: use "git var GIT_EDITOR"

Use the new "git var GIT_EDITOR" feature to decide what editor to
use, instead of duplicating its logic elsewhere.  This should make
the behavior of commands in edge cases (e.g., editor names with
spaces) a little more consistent.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -387,9 +387,7 @@ core.editor::
 	Commands such as `commit` and `tag` that lets you edit
 	messages by launching an editor uses the value of this
 	variable when it is set, and the environment variable
-	`GIT_EDITOR` is not set.  The order of preference is
-	`GIT_EDITOR` environment, `core.editor`, `VISUAL` and
-	`EDITOR` environment variables and then finally `vi`.
+	`GIT_EDITOR` is not set.  See linkgit:git-var[1].
 
 core.pager::
 	The command that git will use to paginate output.  Can

Documentation/git-commit.txt

@@ -323,7 +323,7 @@ ENVIRONMENT AND CONFIGURATION VARIABLES
 The editor used to edit the commit log message will be chosen from the
 GIT_EDITOR environment variable, the core.editor configuration variable, the
 VISUAL environment variable, or the EDITOR environment variable (in that
-order).
+order).  See linkgit:git-var[1] for details.
 
 HOOKS
 -----

Documentation/git-send-email.txt

@@ -60,8 +60,8 @@ The --bcc option must be repeated for each user you want on the bcc list.
 The --cc option must be repeated for each user you want on the cc list.
 
 --compose::
-	Use $GIT_EDITOR, core.editor, $VISUAL, or $EDITOR to edit an
-	introductory message for the patch series.
+	Invoke a text editor (see GIT_EDITOR in linkgit:git-var[1])
+	to edit an introductory message for the patch series.
 +
 When '--compose' is used, git send-email will use the From, Subject, and
 In-Reply-To headers specified in the message. If the body of the message

contrib/fast-import/git-p4

@@ -729,13 +729,10 @@ class P4Submit(Command):
             tmpFile.write(submitTemplate + separatorLine + diff + newdiff)
             tmpFile.close()
             mtime = os.stat(fileName).st_mtime
-            defaultEditor = "vi"
-            if platform.system() == "Windows":
-                defaultEditor = "notepad"
             if os.environ.has_key("P4EDITOR"):
                 editor = os.environ.get("P4EDITOR")
             else:
-                editor = os.environ.get("EDITOR", defaultEditor);
+                editor = read_pipe("git var GIT_EDITOR")
             system(editor + " " + fileName)
 
             response = "y"

git-add--interactive.perl

@@ -987,8 +987,7 @@ sub edit_hunk_manually {
 EOF
 	close $fh;
 
-	my $editor = $ENV{GIT_EDITOR} || $repo->config("core.editor")
-		|| $ENV{VISUAL} || $ENV{EDITOR} || "vi";
+	chomp(my $editor = run_cmd_pipe(qw(git var GIT_EDITOR)));
 	system('sh', '-c', $editor.' "$@"', $editor, $hunkfile);
 
 	if ($? != 0) {

git-send-email.perl

@@ -162,7 +162,8 @@ my $compose_filename;
 
 # Handle interactive edition of files.
 my $multiedit;
-my $editor = $ENV{GIT_EDITOR} || Git::config(@repo, "core.editor") || $ENV{VISUAL} || $ENV{EDITOR} || "vi";
+my $editor = Git::command_oneline('var', 'GIT_EDITOR');
+
 sub do_edit {
 	if (defined($multiedit) && !$multiedit) {
 		map {

git-sh-setup.sh

@@ -99,19 +99,12 @@ set_reflog_action() {
 }
 
 git_editor() {
-	: "${GIT_EDITOR:=$(git config core.editor)}"
-	: "${GIT_EDITOR:=${VISUAL:-${EDITOR}}}"
-	case "$GIT_EDITOR,$TERM" in
-	,dumb)
-		echo >&2 "No editor specified in GIT_EDITOR, core.editor, VISUAL,"
-		echo >&2 "or EDITOR. Tried to fall back to vi but terminal is dumb."
-		echo >&2 "Please set one of these variables to an appropriate"
-		echo >&2 "editor or run $0 with options that will not cause an"
-		echo >&2 "editor to be invoked (e.g., -m or -F for git-commit)."
-		exit 1
-		;;
-	esac
-	eval "${GIT_EDITOR:=vi}" '"$@"'
+	if test -z "${GIT_EDITOR:+set}"
+	then
+		GIT_EDITOR="$(git var GIT_EDITOR)" || return $?
+	fi
+
+	eval "$GIT_EDITOR" '"$@"'
 }
 
 is_bare_repository () {

git-svn.perl

@@ -1321,9 +1321,8 @@ sub get_commit_entry {
 	close $log_fh or croak $!;
 
 	if ($_edit || ($type eq 'tree')) {
-		my $editor = $ENV{VISUAL} || $ENV{EDITOR} || 'vi';
-		# TODO: strip out spaces, comments, like git-commit.sh
-		system($editor, $commit_editmsg);
+		chomp(my $editor = command_oneline(qw(var GIT_EDITOR)));
+		system('sh', '-c', $editor.' "$@"', $editor, $commit_editmsg);
 	}
 	rename $commit_editmsg, $commit_msg or croak $!;
 	{