Class::Accessor::Class

[Class A]
A->Data = A
[Class B inherit A]
B->Data = A
[create new A object : a]
A->Data = A
$a->Data = A
B->Data = A
[input object a->Data = a]
A->Data = a
$a->Data = a
B->Data = a
[create new B object : b]
A->Data = a
$a->Data = a
B->Data = a
$b->Data = a
[B->data = B]
A->Data = B
$a->Data = B
B->Data = B
$b->Data = B
[input object b->Data = b]
A->Data = b
$a->Data = b
B->Data = b
$b->Data = b

クラスのスタティック変数（継承クラスも全て共通）