You could write a sub that would create the temp variable for you and return it: 
#!/usr/bin/perl -w

use strict;

foreach my $str (qw(fish apple license gradual canaan))
{
  print sr($str,'s/([aeiou])/\u$1/g'),"\n";
}

sub sr
{
  my($in,$re)=@_;
  eval "\$in =~ $re;";
  $@ and die "Bad regex '$re'\n";
  $in;
}

[download]
although a temp variable is still being created, just not explicitly.

This is probably the best you're going to be able to do (although there's probably a way to do it without eval), since doing something nondestructively means that the original must be kept intact, so there have to be two copies of the variable.

In reply to Re: Non-destructive string substitution by sgifford
in thread Non-destructive string substitution by Sprad

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