原始的初始化
子类直接调用超类 __init__ 方法初始化，当形成钻石继承的时候，超类会被多次初始化，可能会有意向不到的问题：
BaseClass
/ \
OneClass TwoClass
\ /
TestClass
from pprint import pprint class BaseClass(object):
def __init__(self, a):
# value = a
self.value = a class OneClass(BaseClass):
def __init__(self, a):
BaseClass.__init__(self, a)
# value + 2
self.value += 2 class TwoClass(BaseClass):
def __init__(self, a):
BaseClass.__init__(self, a)
# value * 2
self.value *= 2 class TestClass(TwoClass, OneClass):
def __init__(self, a):
TwoClass.__init__(self, a)
OneClass.__init__(self, a)
# value + 8
self.value += 8
print self.value pprint(TestClass.mro())
test = TestClass(3) #
# 初始化的过程是：BaseClass ——> TwoClass ——> BaseClass ——> OneClass ——> TestClass
# value 的变化： value = 3 ——> value = 6 ——> value = 3 ——> value = 5 ——> value = 13
新类初始化
使用 super 可以解决超类重复初始化的问题，保证超类只被初始化一次：
from pprint import pprint class BaseClass(object):
def __init__(self, a):
# value = a
self.value = a class OneClass(BaseClass):
def __init__(self, a):
super(OneClass, self).__init__(a)
# value + 2
self.value += 2 class TwoClass(BaseClass):
def __init__(self, a):
super(TwoClass, self).__init__(a)
# value * 2
self.value *= 2 class TestClass(TwoClass, OneClass):
def __init__(self, a):
super(TestClass, self).__init__(a)
# value + 8
self.value += 8
print self.value pprint(TestClass.mro())
"""
以以下相反的顺序初始化子类
[<class 'TestClass'>,
<class 'TwoClass'>,
<class 'OneClass'>,
<class 'BaseClass'>,
<type 'object'>]
"""
test = TestClass(3) #
# 初始化的过程是：BaseClass ——> OneClass ——> TwoClass ——> TestClass
# value 的变化： value = 3 ——> value = 5 ——> value = 10 ——> value = 18