Why not just combine the two into one regexp, skirting the issue entirely?

$phrase = '$foo $(bar)';
$variables = { foo => '$(bar)', bar => '$(foo)' };

$phrase =~ s/
    (?:                     # Just take the first one
        \$([a-zA-Z0-9_]+)
    )
    |                       # And alternate it with the second
    (?:
        \$\(([a-zA-Z0-9_]+)\)
    )
    /$variables->{$1||$2}/xg; # Then do the substitution for the one
                              # that matched

print $phrase; # Prints "$(bar) $(foo)"

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I'm sure there's an easier and more efficient way to write this regex, but this seems like the straightforward solution. You eliminate the second pass, so you eliminate the double interpolation. This particular scheme fails if you allow a variable named '0' though, so you may need to do something else in the replacement part if this is the case.

-- David Irving

In reply to Re: How do I avoid double substitution when replacing many patterns? by dirving
in thread How do I avoid double substitution when replacing many patterns? by kyle

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