qr// only compiles regular expressions, not substitution operators. What you've done is compiled a regular expression for matching `s/foo/bar/g'. You can use compiled regexen on the left hand side of an s/// expression, but you can't use one to capture the whole expression.

Now if what you're trying to do is capture an operation or three to be performed on a string that you can select programattically, you possibly could use a hash of coderef like this:

my %mungers = (
            foo => sub { $_[0] =~ s/foo/bar/g },
                fru => sub { $_[0] =~ s/(fru.*)/uc($1)/e },
              );

if( $phase_of_moon > WAXING_GIBBOUS ) {
  $mungers->{foo}->( $string );
} else {
  $mungers->{fru}->( $string );
}

[download]

Update: Feh, as was pointed out that first -> inside the if/else blocks is extraneous. That's what I get for posting while trying to eat breakfast.

In reply to It doesn't mean what you think it means by Fletch
in thread Compiling regular expressions to perform substitution by Stegalex

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.