Use array slicing: 
my %patterns = ( 123 => [0,1,2],
                 312 => [2,1,0] );

my @matches = $string =~ m/$some_pattern/;
return join '', @matches[@{$patterns{$patternkey}}];

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In reply to Re: Double interpolation of captured substrings by Arunbear
in thread Double interpolation of captured substrings by bobf

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