Iterator protocol
Iterative definition:
Iterative feedback process is repeated activities, its purpose is usually to approach a desired result or goal. Each repetition of the process is called an "iteration", and the results will be obtained for each iteration as the initial value for the next iteration.
1 iterator protocol: an object must provide the __next __ () method, the method is performed either returns the next one iteration, or to cause a StopIteration exception to terminate the iteration (forward only, not back)
2 iterables (iterator): iterator object that implements the protocol (how iterator protocol, defined inside the object the __iter __ () method
3 is a protocol convention iterables implements iterator protocol, Python internal function means (for loop, sum, min, max functions, etc.) are iterative protocol used to access the object! ! !
Iterator function: can save memory
The method iterator-related: iter () and the Next () .
python built-in function next () is essentially a call to __next __ ()
List = >>> [1,2,3,4] >>> IT = ITER (List) # iterator object created >>> print (next (it)) # next element of the output iterator 1 >>> Print (Next (IT)) 2 >>>