From dc97b2596fd2429ae31c4c4987127ff48d350a1e Mon Sep 17 00:00:00 2001
From: Mischa POSLAWSKY <perl@shiar.org>
Date: Sat, 10 Dec 2022 01:12:57 +0100
Subject: [PATCH] sum calculation on demand and cached

Automatic handling of any (re)use in calc().
---
 barcat | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/barcat b/barcat
index cb3282e..1fd0dd3 100755
--- a/barcat
+++ b/barcat
@@ -400,11 +400,9 @@ sub show_stat {
 		$vars{partsum} = sum(0, grep {length} @values[$linemin .. $linemax])
 			if $linemin <= $linemax and ($opt{hidemin} or $opt{hidemax});
 		%vars = (%vars,
-			sum => sum(@order),
 			min => $order[-1],
 			max => $order[0],
 		);
-		$vars{avg} = $vars{sum} / @order;
 	}
 	say varfmt($opt{report}, \%vars);
 	return 1;
@@ -413,10 +411,16 @@ sub show_stat {
 sub calc {
 	my ($func) = @_;
 	if ($func eq 'avg') {
-		return sum(@order) / @order;
+		return calc('sum') / @order;
 	}
 	elsif ($func eq 'sum') {
-		return sum(@order);
+		state $cache;         # avoid recount
+		state $cachednr = 0;  # if unchanged
+		unless (@order == $cachednr) {
+			$cache = sum(@order);
+			$cachednr = @order;
+		}
+		return $cache;
 	}
 	elsif ($func =~ /\A([0-9.]+)v\z/) {
 		$1 <= 100 or die(
-- 
2.30.0