The idea is definitely cool, but there are a couple bugs in the execution:

• You set the colors for some elements, but not for all. For people whose color defaults are light-on-dark, it's impossible to read. Luckily, Tk handles standard -fg and -bg options, so this is quickly solved. However, you might want to either completely leave the colors alone (easy), specify them all (medium), or choose your colors to work with the defaults (hard).
• It's great for seeing what substitutions will do, but doesn't seem to work for regexes. With a string of "abbaaba" and a regex "a+", I get "abbaaba".

Also, it would be much cooler if you could show what the regex did element by element. For example, you could turn on /x by default, split the RE on whitespace, and show both what each prefix matches, and what each matches with the rest of the RE as a lookahead assertion (untested):

local $_ = $string_to_match;
my @reparts = split ' ', $re;
my $pre = '';
while (@reparts) {
    $pre .= shift @reparts;
    print "$pre w/ lookahead: ", /$pre (?=@reparts)/x, "\n";
    print "Prefix $pre: ", /$pre/x, "\n";
}
print "Shebang entier: ", /$pre/x, "\n";
[download]

/s

---

---

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! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

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:
	&		&
	<		&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.