Perl Gotcha I

I'm trying to write some interesting, sometimes unexpected, things one can experience with Perl in the next time.
They are partly based on a talk I did at the German Perl Workshop 2008, see my talk in german.


How does the regex

  m/foo$\nbar/m

gets interpreted?

At first it looks like it matches "foo", then end of line with the $, then a newline with \n and finally "bar".
Let' see:

  my $string = "foo\nbar";
  print $string =~/foo$\nbar/m ? 'match':'no match'

Surprisingly the regex does not match like expected.

Explanation:
The regex is interpreted as

  /foo $\ nbar/mx

e.g. it matches "foo", then the content of the special variable $\ (usually undef) and finally "nbar"