python的继承,多继承,经典类的MRO,新式类的MRO,C3算法,super

Posted 2021-01-09 冒蓝火的加特林哒哒哒

#继承
class JiaoFu:
    def qd(self):
        print("教父带你祈祷")
class Fu:
    def msj(self):
        print("alex喜欢msj")

class Zi(Fu, JiaoFu):
    def dbj(self):
        print("刘伟喜欢大宝剑")

z = Zi()
z.msj()
z.dbj()
z.qd()


class Base1: # Base1 object
    def func(self):
        print("娃哈哈")


class Base2:
    def func(self):
        print("雪碧")

class Foo(Base1, Base2): # Foo, Base1, Base2
    pass

f = Base1()
f.func() # 雪碧, 娃哈哈

#经典类的MRO,深度优先
class A:
    pass

class B:
    pass

class C:
    pass

class D:
    pass

class E(A, C):
    pass

class F(B, D):
    pass

class G(E, F):
    pass


# GEACFBD #

#新式类的MRO,C3算法
class A:
    pass
class B(A):
    pass
class C(A):
    pass
class D(B, C):
    pass
class E(C, A):
    pass
class F(D, E):
    pass
class G(E):
    pass
class H(G, F):
    pass
print(H.__mro__)
# H的MRO: ??
# 拆
# L(H)= H + L(G) + L(F) -> H + (GECA) + (FDBECA) -> HGFDBECA (MRO)
#
# # L(G) = G + L(E) -> G +(ECA) -> GECA
# # L(F) = F + L(D) + L(E) -> F +(DBCA) + (ECA) -> FDBECA
#
# # L(E) = E +  L(C) + L(A) -> E + (CA) + A -> ECA
# # L(D) = D + L(B)+ L(C)  -> D + (BA) + (CA) -> DBCA
#
# # L(c) = C + A  CA
# # L(B) = B + A  BA
#
# # L(A) = A



#实例
class A:
    pass
class B(A):
    pass
class C(A):
    pass
class D(B, C):
    pass
class E(C, A):
    pass
class F(D, E):
    pass
class N:
    pass
class O:
    pass
class M(N, O):
    pass
class G(E, M):
    pass
class H(G, F):
    pass

print(H.__mro__)

# H的MRO
L(H) = H + L(G) + L(F) -> H + (MNO) + () -> H G F D B E C A M N O

L(G) = G + L(E) + L(M)  -> G + (ECA) + (MNO) -> GECAMNO
L(F) = F + L(D) + L(E)  -> F + (DBCA) + (ECA) -> FDBECA

L(E) = E + (CA) + A -> ECA
L(M) = M + N + O  -> MNO
L(D) = D + (BA) + (CA) -> DBCA

H G F D B E C A M N O

# MRO + super ⾯试题
class Init(object):
    def __init__(self, v):
        print("init")
        self.val = v
class Add2(Init):
    def __init__(self, val):
        print("Add2")
        super(Add2, self).__init__(val)
        print(self.val)  # 5
        self.val += 2 # 7
class Mult(Init):
    def __init__(self, val):
        print("Mult")
        super(Mult, self).__init__(val)
        self.val *= 5
class HaHa(Init):
    def __init__(self, val):
        print("哈哈")
        super(HaHa, self).__init__(val)
        self.val /= 5
class Pro(Add2,Mult,HaHa): #
    pass
class Incr(Pro):
    def __init__(self, val):
        super(Incr, self).__init__(val)
        self.val += 1

print(Incr.__mro__)#得到mro继承列表


# p = Incr(5)  # MRO: Incr Pro Add2 Mult HaHa Init
# # 一个对象. p :  val: 8
# print(p.val)
c = Add2(2) # MRO: ADD2 INIT
print(c.val)

class haha(object):pass
class base(object):pass
class foo(base,haha):pass
print(foo.__bases__)#获取当前类的父类返回一个元组（base,haha）