Re^3: Perl Number range lookup question

[tobyink]

my $tier = $tiers{$n} //= calculate_tier($n);

That's a rather elegant memoization technique for functions in general (provided the function parameters can't be references). If your function took two parameters, you could even do:

my $tier = $tiers{$n, $m} //= calculate_tier($n, $m);

... taking advantage of Perl's rarely used multi-dimensional array fakery.