python继承

子类不会默认调用父类的构造函数,但如果子类没有自己的构造函数则会默认调用父类的

class P(object):
    def __init__(self):
        print 'P inited'
    def __del__(self):
        print 'P deleted'
    def fun(self):
        print 'P fun'
        
class C(P):
    def __init__(self):
        print 'C inited'
    def __del__(self):
        print 'C deleted'
    def fun(self):
        super(C,self).fun()
        print 'C fun'

class C2(P):
    pass

>>> c = C()
C inited
>>> c.fun()
P fun
C fun
>>> delete c
SyntaxError: invalid syntax
>>> del c
C deleted
>>> c2 = C2()
P inited

多重继承，先继承的优先调用

class P1:
    def __init__(self):
        print 'P1 init()'
    def foo(self):
        print 'P1 foo()'

class P2:
    def __init__(self):
        print 'P2 init()'
    def foo(self):
        print 'P2 foo()'
    def bar(self):
        print 'P2 bar()'

class C1(P1,P2):
    pass
class C2(P2,P1):
    def bar(self):
        print 'C2 bar()'

class GC(C1,C2):
    pass


>>> c1 = C1()
P1 init()
>>> c2 = C2()
P2 init()
>>> c1.foo()
P1 foo()
>>> c1.bar()
P2 bar()
>>> c2.foo()
P2 foo()//先继承了P2，所以优先调用P2的foo
>>> c2.bar()
C2 bar()
>>> gc = GC()
P1 init()
>>> gc.foo
<bound method GC.foo of <__main__.GC instance at 0x0000000002F55588>>
>>> gc.foo()
P1 foo()//先继承了C1,C1再向上找到P1的foo
>>> gc.bar()
P2 bar()
>>>