package StaticClass;

my $attrib = '...';

# print StaticClass->method();
sub method {
    my ($class) = @_;
    return $attrib;
}

1;

##</code><code>##

package SingletonClass;

my $singleton;

sub new {
    return $singleton ||= bless({
        attrib => '...',
    });
}

# print $obj->method();
sub method {
    my ($self) = @_;
    return $self->{attrib};
}

1;