# require outside the package so that its functions are 
# NOT imported into the UtilLib namespace, so that other
# libraries can use them.
require mysql_wrapper_lib.pl;

package UtilLib;

##</code><code>##

# File mysql_wrapper_lib.pl
$foo = 123;
1;

##</code><code>##

package One;
use UtilLib;

package Two;
use UtilLib;

##</code><code>##

# File Mysql_wrapper.pm
package Mysql_wrapper;
use base 'Exporter';
@EXPORT = qw($foo);

$foo = 123;
1;

##</code><code>##

package One;
use Mysql_wrapper;

package Two;
use Mysql_wrapper;

##</code><code>##

package Mysql_wrapper;
$foo = 123;

sub import {
   my $pkg = caller;
   no strict 'refs';
   *{"$pkg\::foo"} = \$foo;
   # and the same for other variables...
}
1;