vars - Perl pragma to predeclare global variable names
use vars qw($frob @mung %seen);
This will predeclare all the variables whose names are in the list, allowing you to use them under ``use strict'', and disabling any typo warnings.
Unlike pragmas that affect the $^H hints variable, the use vars and
use subs declarations are not BLOCK-scoped. They are thus effective for the entire
file in which they appear. You may not rescind such declarations with no vars or no subs.
Packages such as the AutoLoader and SelfLoader that delay loading of subroutines within packages can create problems with
package lexicals defined using my(). While the vars pragma cannot duplicate the effect of package lexicals (total transparency
outside of the package), it can act as an acceptable substitute by
pre-declaring global symbols, ensuring their availability to the
later-loaded routines.
See perlmodlib.