How can a package knows which path it is in?

For example, I have a "test.pm" in "/www/somedir":

package test;
sub currDIR {
   use Cwd;
   print getcwd();
}

and then a "main.cgi" in "/www":

require "./somedir/test.pm";
test::currDIR();

running main.cgi will print me "/www" (path to main.cgi), however, I actually want "/www/somedir" (path to test.pm) instead, which command should I use?  I'm asking this because I need to open certain files in the package, and those files are stored in the same directory as the package for portability issues.  Thank you.