定义 Python 中类变量的正确方式是什么?


类变量是在__init__方法外部声明的变量。它们是静态元素,这意味着它们属于类而不是类实例。这些类变量由该类的所有实例共享。类变量的示例代码 

实例

class MyClass:
  __item1 = 123
  __item2 = "abc"
  def __init__(self):
    #pass or something else

通过更多代码,你会有更清晰的了解 −

class MyClass:
    stat_elem = 456
    def __init__(self):
        self.object_elem = 789
c1 = MyClass()
c2 = MyClass()
# Initial values of both elements
>>> print c1.stat_elem, c1.object_elem
456 789
>>> print c2.stat_elem, c2.object_elem
456 789
# Let's try changing the static element
MyClass.static_elem = 888
>>> print c1.stat_elem, c1.object_elem
888 789
>>> print c2.stat_elem, c2.object_elem
888 789
# Now, let's try changing the object element
c1.object_elem = 777
>>> print c1.stat_elem, c1.object_elem
888 777
>>> print c2.stat_elem, c2.object_elem
888 789

更新于: 2020-01-03

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