There is a cleaner way, but you still need the temporary variable to preserve $string. I assume you need $string later which is the only reason you'd need a non-destructive substitution. You can declare and substitute in one step: 
(my$tmp = $string) =~ s/foo/blah/;

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In reply to Re: Non-destructive substitution? by epoptai
in thread Non-destructive substitution? by Sprad

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