package Foo::Bar;
  use base 'Foo';

  sub foosub {
    my $self   = shift;
    my $FooObj = Some::Module->new;
    die "Not an object!" unless ref $FooObj eq 'Some::Module';

    $self->barsub( $FooObj );
    }

  sub barsub {
    my $self   = shift;
    my $FooObj = shift;
	
    ...
    }