Python MRO C3算法实现
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算法实现
#-*- encoding:GBK -*-#def mro_C3(*cls): if len(cls)==1: if not cls[0].__bases__: return cls else: return cls+ mro_C3(*cls[0].__bases__) else: seqs = [list(mro_C3(C)) for C in cls ] +[list(cls)] res = [] while True: non_empty = list(filter(None, seqs)) if not non_empty: return tuple(res) for seq in non_empty: candidate = seq[0] not_head = [s for s in non_empty if candidate in s[1:]] if not_head: candidate = None else: break if not candidate: raise TypeError("inconsistent hierarchy, no C3 MRO is possible") res.append(candidate) for seq in non_empty: if seq[0] == candidate: del seq[0]?测试一
#####################测试1 ob=objectclass A(ob): passclass B(ob): pass class X(A,B): passclass Y(A,B): passtry: class Z(X,Y): pass print Z.mro() print Z.__mro__ print mro_C3(Z)except :pass try: print mro_C3(X,Y)#如果从X,Y继承，它的MRO值是什么except Exception,e: print e ######打印结果 [<class '__main__.Z'>, <class '__main__.X'>, <class '__main__.Y'>, <class '__main__.A'>, <class '__main__.B'>, <type 'object'>](<class '__main__.Z'>, <class '__main__.X'>, <class '__main__.Y'>, <class '__main__.A'>, <class '__main__.B'>, <type 'object'>)(<class '__main__.Z'>, <class '__main__.X'>, <class '__main__.Y'>, <class '__main__.A'>, <class '__main__.B'>, <type 'object'>)(<class '__main__.X'>, <class '__main__.Y'>, <class '__main__.A'>, <class '__main__.B'>, <type 'object'>)?
测试二
#####################测试2 ob=objectclass A(ob): passclass B(ob): pass class X(A): passclass Y(B): passtry: class Z(X,Y): pass print Z.mro() print Z.__mro__ print mro_C3(Z)except :pass try: print mro_C3(X,Y)#如果从A,B继承，它的MRO值是什么except Exception,e: print e ####打印结果 [<class '__main__.Z'>, <class '__main__.X'>, <class '__main__.A'>, <class '__main__.Y'>, <class '__main__.B'>, <type 'object'>](<class '__main__.Z'>, <class '__main__.X'>, <class '__main__.A'>, <class '__main__.Y'>, <class '__main__.B'>, <type 'object'>)(<class '__main__.Z'>, <class '__main__.X'>, <class '__main__.A'>, <class '__main__.Y'>, <class '__main__.B'>, <type 'object'>)(<class '__main__.X'>, <class '__main__.A'>, <class '__main__.Y'>, <class '__main__.B'>, <type 'object'>)?
测试三
#####################测试3 ob=objectclass A(ob): passclass B(ob): pass class X(A,B): passclass Y(B,A): passtry: class Z(X,Y): pass print Z.mro() print Z.__mro__ print mro_C3(Z)except :pass try: print mro_C3(X,Y)#如果从A,B继承，它的MRO值是什么except Exception,e: print e##打印结果 报错了，无法 定义 类 Zinconsistent hierarchy, no C3 MRO is possible?