package Foo;
use strict;
our (@ISA,@EXPORT,@EXPORT_OK);
BEGIN {
  require Exporter;
  @ISA = qw(Exporter);
  @EXPORT = qw(SOME CONST VARS);
  @EXPORT_OK = qw(bar);
};

use constant (
  SOME => 1
 ,CONST => 2
 ,VARS  => 42
);

sub bar {
  .
  .
  .
}

1;