#__contains__优于__iter__优于__getitem__方法
#__contains__方法应该把成员关系定义为对一个映射应用键(并且可以使用快速查找),以及用于序列的搜索
class Iters:
def __init__(self, value):
self.data=value
def __getitem__(self, i):
print('get[%s]:'%i, end=' ')
return self.data[i]
def __iter__(self):
print('iter=>', end=' ')
self.ix=0
return self
def __next__(self):
print('next:', end=' ')
if self.ix==len(self.data):
raise StopIteration
item=self.data[self.ix]
self.ix+=1
return item
def __contains__(self, x): #in 和not in 操作的时候会自动调用这个函数
print('contains: ',end=' ')
return x in self.data
x=Iters([1,2,3,4,5])
print(3 in x) #contains: True
for i in x:
print(i, end=', ') #iter=> next: 1, next: 2, next: 3, next: 4, next: 5, next:
print()
print([i**2 for i in x]) #iter=> next: next: next: next: next: next: [1, 4, 9, 16, 25]
print(list(map(bin,x))) #iter=> next: next: next: next: next: next: ['0b1', '0b10', '0b11', '0b100', '0b101']
i=iter(x)
while True:
try:
print(next(i), end=' @ ') #iter=> next: 1 @ next: 2 @ next: 3 @ next: 4 @ next: 5 @ next:
except StopIteration:
break
print()
print(x[0]) #get[0]: 1 __getitem__支持索引
print(x[:-1]) #get[slice(None, -1, None)]: [1, 2, 3, 4]
python 成员关系:__contains__,__iter__和__getitem__
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转载自blog.csdn.net/ljyljyok/article/details/105257817
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