python中的__len__,__getitem__ __setitem__ __delitem__ __contains__

class TemTest:
def __init__(self,):
        self.x=[i for i in range(10)]
def __len__(self):
        return len(self.x)
def __getitem__(self, item):
        return self.x[item]
def __setitem__(self, key, value):
        self.x[key]=value
def __delitem__(self, key):
        del self.x[key]
def __contains__(self, item):
        return item in self.x
def __repr__(self):
        return '{}'.format(self.x)

test=TemTest() #实例化
print(len(test)) #返回长度


print(test[0])   #打印下标0的值
print(test[:3])  #切片


test[3]=10       #将下标3的值替换为10
print(test)


del test[3]      #删除下标3的值
print(test)


print(1 in test)  #测试in运算符
print(3 in test)  

10
0
[0, 1, 2]
[0, 1, 2, 10, 4, 5, 6, 7, 8, 9]
[0, 1, 2, 4, 5, 6, 7, 8, 9]
True
False