Question

我是Python的初学者，我正在寻找一种方法来创建一个带有子属性的类，这样我就可以将公共属性组合在一起并引用主类。例如：

class RoadNetwork(object): # This is the main class
    def __init__(self):
        self.Types = ['Dirt', 'Gravel', 'Pavement']

    class HighWay(self): # This is the subclass
        def __init__(self):
            MaxSpeed = 55
            MinSpeed = 35
            Type = self.Types[2]


>>> roads = RoadNetwork()
>>> roads.Types
['Dirt', 'Gravel', 'Pavement']
>>> roads.HighWay.MaxSpeed
55
>>> roads.HighWay.MinSpeed
35
>>> roads.HighWay.Type
'Pavement'
>>>

Answer 1

你遗产错了。这就是你应该如何声明一个类层次结构：

class RoadNetwork(object):  # This is the main class
    def __init__(self):
        self.types = ['Dirt', 'Gravel', 'Pavement']

class HighWay(RoadNetwork): # This is the subclass
    def __init__(self):
        RoadNetwork.__init__(self)
        self.maxSpeed = 55
        self.minSpeed = 35
        self.roadType = self.types[2]

例如：

road = RoadNetwork()
road.types
=> ['Dirt', 'Gravel', 'Pavement']

highway = HighWay()
highway.maxSpeed
=> 55
highway.minSpeed
=> 35
highway.roadType
=> 'Pavement'

Answer 2

我并不认为继承是你正在寻找的，因为HighWay是一种道路，但它不是一种RoadNetwork。据我了解，您只需要RoadNetwork的单个实例，并且您的道路类型都会引用同一个RoadNetwork实例。

我还建议将一些实例变量移动到类属性中。例如，HighWay的所有实例都具有相同的roadType，因此它们不会在实例级别分配，而是共享类值。

执行此操作的最简单方法可能是让所有道路类型引用全局变量roads，但通常会以这种方式使用全局变量。更好的解决方案是使用类工厂，将引用传递给RoadNetwork实例：

def highway_factory(roads):
    class HighWay(object):
        max_speed = 55
        min_speed = 35
        road_type = roads.types[2]
    return HighWay

class RoadNetwork(object):
    def __init__(self):
        self.types = ['Dirt', 'Gravel', 'Pavement']
        self.HighWay = highway_factory(self)

示例：

>>> roads = RoadNetwork()
>>> roads.types
['Dirt', 'Gravel', 'Pavement']
>>> roads.HighWay.max_speed
55
>>> roads.HighWay.min_speed
35
>>> roads.HighWay.road_type
'Pavement'

具有子属性的Python类（初学者）

2 个答案: