python之继承

1.经典mro : 树形结构的深度遍历优先 - > 树形结构遍历

class a:
    pass
class b(a):
    pass
class c(a):
    pass
class d(b, c):
    pass
class e:
    pass
class f(d, e):
    pass
class g(f, d):
    pass
class i:
    pass
class j(b, c): 
    pass
class k(a):
    pass
class h(i, j, k):
    pass
class foo(h, g):
    pass

流程图:

 类的mro: foo -> h -> i->  j->  b->  a->  c->  k->  g->  f->  d->  e 

2.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 m:
    pass
class n(m):
    pass
class p(e, a):
    pass
class x:
    pass
class q(p, n, x):
    pass
class g(q, f):
    pass
class h(g, f):
    pass
print(h.__mro__)
'''
(<class '__main__.h'>, <class '__main__.g'>, <class '__main__.q'>, <class '__main__.p'>,
<class '__main__.f'>, <class '__main__.d'>, <class '__main__.b'>, <class '__main__.e'>, 
<class '__main__.c'>, <class '__main__.a'>, <class '__main__.n'>, <class '__main__.m'>, 
<class '__main__.x'>, <class 'object'>)
'''

c3算法:

　　l(h) = h + l(g) + l(f) + gf # hgqpfdbecanmx

　　l(g) = g + l(q) + l(f) + qf # gqpfdbecanmx 
　　l(q) = q + l(p) + l(n) + x + pnx # qpecanmx
　　l(p) = p + l(e) + a + ea  # peca
　　l(e) = e + l(c) + a + ca   # eca
　　l(c) = c + a + a   # ca
　　l(n) = n + m # nm

　　l(f) = f + l(d) + l(e) + de # fdbeca
　　l(d) = d + l(b) + l(c) + bc # dbca

 加法:merge(), 拿第一项的第一位和 后面每项的除了第一位比较. 如果没有出现, 则该位元素算出
    如果出现了. 此时开始下一项的第一位继续和后面每一项的除了第一位比较:

　　　　中心思想:用头和后面身体比较