/me kneels before the Perl monks...

After asking the resident Perl geeks, I turn to you for wisdom. What is the Right Way to use a variable as a basis for an s///, without modifying it? 
    $foo = "bar baz";
    (my $qux = $foo) =~ s/bar/quux/;

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Here $foo is unchanged, and $qux equals "quux baz". Is there a more elegant way to do this, e.g. without first copying $foo?

(BTW, brother dep informs me that using 'my' inside of the parentheses is not a good thing. Maybe that's why I insist on doing it that way... ;] What traps can I run in to doing that?)

In reply to Substituting without modifying by crackhed

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