note Ovid <p>The Orcish Maneuver is a term coined by Joseph Hall in his book "Effective Perl Programming" (co-authored by [merlyn]). Here's the essence of it:</p> <code> my @sorted = sort { ( $times{$a} ||= -M $a ) <=> ( $times{$b} ||= -M $b ) } @old_array; </code> <p>The "orcish" (a bad attempt at humor: "or cache") maneuver basically caches the results of an expensive lookup using the ||= operator. This operator says, in the above code, that $times{$a} will be evaluated or, if it is false, set it to the value of -M $a. (-M is the file test operator for last modified time). This allows you to cache the results of -M rather than call it every time. This has the same effect as:</p> <code> for ( @old_array ) { $times{ $_ } = -M $_; } my @sorted = sort { $times{$a} <=> $times{$b} } @old_array; </code> <p>Cheers,<br /> <a href="/index.pl?node=Ovid&lastnode_id=1072">Ovid</a></p> <p><small>Join the <a href="http://setiathome.ssl.berkeley.edu/stats/team/team_86606.html">Perlmonks Setiathome Group</a> or just click on the the link and check out our stats.</small></p> 129788 130021