Re: Harmful LESS flags

From: Jeff King <peff@peff.net>
Date: Apr 24, 2014, 21:35 UTC
Message-ID: <20140424213529.GB7815@sigill.intra.peff.net>
In-Reply-To: <xmqq8uquv84u.fsf@gitster.dls.corp.google.com>

On Thu, Apr 24, 2014 at 12:29:21PM -0700, Junio C Hamano wrote:

Show 16 quoted lines

> David Kastrup <dak@gnu.org> writes:
> 
> > Junio C Hamano <gitster@pobox.com> writes:
> >
> >> Traditionally, because the tool grew in a context of being used in a
> >> project whose participants are at least not malicious, always having
> >> to be on the lookout for fear of middle-of-line tabs hiding bad
> >> contents near the right edges of lines has never been an issue.
> >
> > My beef is not with "hiding bad contents" but with "hiding contents".
> > It makes the output useless for seeing what is actually happening as
> > soon as the option starts having an effect.
> 
> My suspicion is that one of the reasons why S was chosen to be in
> the default was to mildly discourage people from busting the usual
> line-length limit, but I am not Linus ;-)

I would think it's the opposite. Long lines look _horrible_ without "-S", as they get wrapped at awkward points. Using "-S" means that long lines don't bug you, unless you really want to scroll over and see the content.

I really think the right solution here is to teach less to make it more obvious that there is something worth scrolling over to. Here's a very rough patch for less, if you want to see what I'm thinking of.

diff --git a/input.c b/input.c
index b211323..01aa411 100755
--- a/input.c
+++ b/input.c
@@ -178,6 +178,7 @@ get_forw_line:
 			 */
 			if (chopline || hshift > 0)
 			{
+				set_chopped_marker(ch_tell()-1);
 				do
 				{
 					if (ABORT_SIGS())
diff --git a/line.c b/line.c
index 1eb3914..b3358a0 100755
--- a/line.c
+++ b/line.c
@@ -1080,6 +1080,20 @@ set_status_col(c)
 	attr[0] = AT_NORMAL|AT_HILITE;
 }
 
+	public void
+set_chopped_marker(pos)
+	    POSITION pos;
+{
+	/*
+	 * Roll back output by one character; probably
+	 * we need to actually walk curr back further
+	 * for multibyte characters?
+	 */
+	column--;
+	curr--;
+	store_char('>', AT_NORMAL|AT_HILITE, NULL, pos);
+}
+
 /*
  * Get a character from the current line.
  * Return the character as the function return value,

-Peff