Python扩展内置类型详解

 #File setwrapper.py class Set: def __init__(self,value=[]):#构造函数 self.data = [] self.concat(value) def intersect(self,other):#求交集 res = [] for x in self.data: if x in other: res.append(x) return Set(res) #返回一个新的Set def union(self,other):#求并集 res = self.data[:] #复制self.data for x in other: if not x in res: res.append(x) return Set(res) def concat(self,value): for x in value: if not x in self.data: self.data.append(x) def __len__(self): # len(self) return len(self.data) def __getitem__(self,key): # self[i] return self.data[key] def __and__(self,other): # self & other return self.intersect(other) def __or__(self,other): # self | other return self.union(other) def __repr__(self): # print return 'Set:' + repr(self.data) if __name__ == '__main__': #测试用例 x = Set([1,3,5,7]) print(x.union(Set([1,4,7]))) print(x | Set([1,4,6])) print(x[2]) print(x[2:4]) 

 # File typesubclass.py #Map 1..N to 0..N-1; call back to built-in version class MyList(list): def __getitem__(self,offset): print('(indexing %s at %s)'%(self,offset)) return list.__getitem__(self,offset-1) if __name__ == '__main__': print(list('abc')) x = MyList('abc') print(x) print(x[1]) print(x[3]) x.append('spam') print(x) x.reverse() print(x)