tachyon compares three methods of assigning regexes to a variable: 
$pat = "m/foo/";
print "foo1\n" if "foo" =~ $pat;

$pat = m/foo/;
print "foo2\n" if "foo" =~ $pat;

$pat = qr/foo/;
print "foo3\n" if "foo" =~ m/$pat/;

[download]
Passing $pat into a sub is no problem using either of the second two methods above. The first does not work period as you will see if you run it.
The second does not work either. It is equivalent to: 
$pat = ($_ =~ m/foo/);
print "foo2\n" if "foo" =~ $pat;

[download]
$pat will be either 1 or the null string, depending on whether $_ matches /foo/. You will see this if you run it and actually examine the value of $pat.

In reply to Re: Re: Dynamic Regex? by chipmunk
in thread Dynamic Regex? by footpad

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.