On one of my machines, two of the characters you proposed aren't displayed correctly, because there's no font installed that contains them.

As a maintainer of code like that I would be unhappy to be faced with characters that I don't know how to produce with the keyboard.

In my humble opinion, the real problem with regex readability is that people tend to not reuse regexes, so everything is pieced together from the primitives.

I find 

use Regexp::Common qw /URI/;
if ($string =~/$RE{URI}{HTTP}/) {
    ...
}

[download]

more readable than any of the alternatives you have offered, and there are no "weird" characters involved.

Perl 6 - second systems done right

In reply to Re: Demarcate Regexes with Unicode by moritz
in thread Demarcate Regexes with Unicode by toro

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.