通过列表引用类实例

Question

我有两节课。 Province 创建一堆 Areas 实例，并将它们放入其 self.areas 列表中。我想让Areas 实例访问Province 实例的属性（或其他数据），该实例包含在其self.areas 列表中。可视化：

class Province:
    def __init__(self, stuff="spam"):
        self.stuff = stuff
        self.areas = list()
    def makeareas(self):
        # make instances of Areas and put them in self.areas

class Areas:
    def __init__(self):
        pass
    def access_stuff(self):
        # access stuff of the Province where it is in its list

我该如何做到这一点？更重要的是，这甚至是正确的方法吗？有没有我不知道的更合理、更简单的方法来做到这一点？

Answer 1

在实例化 Area 时，将引用传递给 province，例如：

代码：

class Province:
    def __init__(self, stuff="spam"):
        self.stuff = stuff
        self.areas = list()

    def makeareas(self, area):
        self.areas.append(Areas(area, self))

class Areas:
    def __init__(self, area, province):
        self.area = area
        self.province = province

    def access_stuff(self):
        # access stuff of the Province where it is in its list
        return '%s - %s ' %(self.area, self.province.stuff)

测试代码：

p = Province('This is stuff')
# Examples
p.makeareas('area1')
p.makeareas('area2')

for area in p.areas:
    print(area.access_stuff())

结果：

area1 - This is stuff 
area2 - This is stuff