This class module binds one or more subroutines of your devising to a Perl
variable. All variables can have FETCH, STORE and DESTROY callbacks.
Additionally, arrays can define CLEAR, DELETE, EXISTS, EXTEND, FETCHSIZE,
POP, PUSH, SHIFT, SPLICE, STORESIZE and UNSHIFT callbacks, and hashes can
define CLEAR, DELETE, EXISTS, FIRSTKEY and NEXTKEY callbacks.

With Tie::Watch you can:
* alter a variable's value
* prevent a variable's value from being changed
* invoke a Perl/Tk callback when a variable changes
* trace references to a variable

WWW: http://search.cpan.org/dist/Tie-Watch/
Author:	Steve Lidie <sol0@Lehigh.EDU>