On the other hand, an alternating regex can use the /o modifier, while your version can't. Regex compilation is a costly operation, so alternation should be much faster under /o. 
   MeowChow                                   
               s aamecha.s a..a\u$&owag.print

In reply to Re: Re: Re: using a hash to do substitution? by MeowChow
in thread using a hash to do substitution? by mr.dunstan

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