In terms of expressing intent, at least in my biased opinion, the original code fragment wins, and the attempts at "making it better" are increasingly obfuscating. Unless performance is a serious issue, clarity of expression should be the goal.

Consider picking up the code blind. Which is easier to understand? 

   foreach $oldkey (keys %fdat) {
       if ( ($newkey = $oldkey) =~ s/^redirect_//) {
           $fdat{$newkey} = $fdat{$oldkey};
       }
   }
or
   $fdat{$_} = $fdat{"redirect_$_"} 
       for map { /^redirect_(.*)$/ ? $1 : () } keys %fdat;
I consider myself a pretty fair Perl coder, but I have to admit that it took me an order of magnitude longer to grasp the intent of the second example than it did the first. When I catch folks in my team writing code like the second example, we have a talk. The talk includes asking them to consider the plight of the poor soul who has to pick up the code next.

Clarity, please.

In reply to Expressing Intent by dws
in thread Regexs on Hash Keys by Maclir

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