package MyPackage::Module;

sub new {
    .  .  .  

  bless $self, $class;
}

sub this_method {

}

sub that_method {

}

1;

package MyPackage::Module::ThisFeature;

use base MyPackage::Module;

sub this_method {

}

sub some_other_method {

}

1;

package MyPackage::Module::ThatFeature;

use base MyPackage::Module;

sub that_method {

}

sub still_another_method {

}

1;