# use Constants
use constant EXCEL => 'Excel.Application';
use constant WORD => 'Word.Application';

my $excel = Win32::OLE->GetActiveObject(&WORD)

##</code><code>##

#Use another package
package MSApps;
{
  our $MSApps::EXCEL = 'Excel.Application';
  our $MSApps::WORD = 'Word.Application';
}

## Then
use MSApps;
my $excel = Win32::OLE->GetActiveObject($MSApps::EXCEL)

##</code><code>##

#Do the most simple thing: create variables.
my $EXCEL = 'Excel.Application';
my $WORD = 'Word.Application';

my $excel = Win32::OLE->GetActiveObject($WORD)