考虑这些课程：
class ParentComponent<T> {}
class ChildComponent<T> extends ParentComponent<T> {}
class Parent<C extends ParentComponent> { C component() {return null;} }
class Child<T> extends Parent<ChildComponent<T>> {}
和Child类的实例化：
Child a = new Child();
ChildComponent ac = a.component(); // COMPILE ERROR! actual type is ParentComponent
Child<?> b = new Child<>();
ChildComponent bc = b.component(); // OK
Child<Object> c = new Child<>();
ChildComponent<?> cc = c.component(); // OK
Child<T> extends Parent<ChildComponent<T>> Child如何与ParentComponent成为Child？
为什么java需要至少指定通配符才能推断出类型？
Isn＆f; Child<Object>相当于Child<?>，而@api.multi
@api.onchange('order_lines', 'order_lines.is_book_block', '')
@api.constrains('order_lines', 'order_lines.isbn')
def check_quantity(self):
location = self.printer_book_block.property_stock_supplier.id
for rec in self:
if rec.order_lines:
for line in rec.order_lines:
if line.qty > line.isbn.with_context({ 'location': location, }).qty_available >= 0:#line.isbn.qty_available in location:
rec.write({'state': 'awaitingraw'})
else:
rec.write({'state': 'work_in_progress', 'is_book_block': True})
相当于work_in_progess？