vladb is right on as to the proper way to do this, but I thought I would comment on why it works that way.

When you ran your code, you probably got this error:

Eval-group not allowed at runtime, use re 'eval' in regex m/some((?{pr
+int "Hey!";})/ at - line 6.

[download]
Basically, Perl really doesn't like running code that was interpolated into a string. Since a scalar used in a regex could very likely be input by a user, Perl avoids doing any sort of double interpolation (first interpolate the scalar into the regex, then run the code). If you do put
use eval 're';

[download]
because you know what you're doing, and put the paren at the end of the string that you seemed to forget, the code does what you expect.

In reply to Re: RegEx Perl Code by Ionitor
in thread RegEx Perl Code by Jaspersan

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.