class LineItem(model.Entity):
description = model.NonBlank()
weight = model.Quantity()
price = model.Quantity()
def __init__(self, description, weight, price):
self.description = description
self.weight = weight
self.price = price
def subtotal(self):
return self.price * self.weight
class LineItem(
model.Entity
): #<-model.Entity의 메타클래스 EntityMeta가 v6에서 데코레이터의 역할을 한다. 서브클래스에도 메타클래스가 확실히 적용되기 때문에, 간단히 Entity를 상속한다.
description = model.NonBlank()
weight = model.Quantity()
price = model.Quantity()
def __init__(self, description, weight, price):
self.description = description
self.weight = weight
self.price = price
def subtotal(self):
return self.weight * self.price
class LineItem(model.Entity):
"""
定制描述符的元类，有了元类的支持，集成model.Entity类即可::
>>> raisins = LineItem('Golden raisins', 10, 6.95)
>>> LineItem.description.storage_name
'_NonBlank#description'
>>> raisins.description
'Golden raisins'
>>> getattr(raisins, '_NonBlank#description')
'Golden raisins'
"""
description = model.NonBlank()
weight = model.Quantity()
price = model.Quantity()
def __init__(self, description, weight, price):
self.description = description
self.weight = weight
self.price = price
def subtotal(self):
return self.weight * self.price
class LineItem(model.Entity):
'''
>>> raisins = LineItem('Golden raisins', 10, 6.95)
>>> dir(raisins)[:3]
['_NonBlank#description', '_Quantity#price', '_Quantity#weight']
>>> LineItem.description.storage_name
'_NonBlank#description'
>>> raisins.description
'Golden raisins'
>>> getattr(raisins, '_NonBlank#description')
'Golden raisins'
'''
description = model.NonBlank()
weight = model.Quantity()
price = model.Quantity()
def __init__(self, description, weight, price):
self.description = description
self.weight = weight
self.price = price
def subtotal(self):
return self.weight * self.price