1. 程式人生 > >MRO,C3演算法

MRO,C3演算法

 1瞭解python2和python3類的區別
python2在2.4之前使用的是經典類, 2.4之後, 使用的是新式類

class Foo:
pass

class Foo(object):
pass

MRO: method resolution order 方法的查詢順序

class Base:
pass

class Base1:
def chi():
pass

class Bar(Base, Base1):
pass

b = Bar() # Bar -> Base -> Base1
b.chi()


2. 經典類的MRO 樹形結構的深度優先遍歷 -> 樹形結構遍歷

3. 新式類的MRO C3演算法(難點, 重點)
1. 拆分
2. 合併

用頭和身體比較
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

# L(A) = A
# L(B) = B + L(A) + A
# L(C) = C + L(A) + A
# L(D) = D + L(B) + L(C) + BC
# L(E) = E + L(C) + L(A) + CA
# L(F) = F + L(D) + L(E) + DE
# L(M) = M
# L(N) = N + L(M) + M
# L(P) = P + L(E) + L(A) + EA
# L(X) = X
# L(Q) = Q + L(P) + L(N) + L(X) +PNX
# L(G) = G + L(Q) + L(F) + QF
# L(H) = H + L(G) + L(F) + GF
#
# 
# L(A) = A
# L(B) = B + L(A) + A             # BA
# L(C) = C + L(A) + A             # CA
# L(D) = D + L(B) + L(C) + BC     # DBCA
# L(E) = E + L(C) + L(A) + CA     # ECA
# L(F) = F + L(D) + L(E) + DE     # FDBECA
# L(M) = M
# L(N) = N + L(M) + M             # NM
# L(P) = P + L(E) + L(A) + EA     # PECA
# L(X) = X
# L(Q) = Q + L(P) + L(N) + L(X) +PNX  # QPECANMX
# L(G) = G + L(Q) + L(F) + QF     # GQPFDBECANMX
# L(H) = H + L(G) + L(F) + GF     # HGQPFDBECANMX