Python: Generator function

generator function : a function containing yield statements;

Builder Object : The Builder object behaves similarly to the iterator object and supports an iterative interface: __next__ (), which requires an iterative protocol ' if you want to execute the internal statement of the generator function.

a, when the generator function is called , does not execute the function inner statement, but returns a generator object;

B, each execution of a statement, returns a corresponding yield value, although the function is a yield temporarily returned value, but retains the state of the program run, that is, when executing g.__next__ (), the execution of the function statement, and return the second yield corresponding value When all yield return values are executed, the program throws a stop iteration exception: stopiterstion; This behavior, like iterators, implements an interface for iterators.

deff ():Print('in F (), 1')    yield1Print('in F (), 2')    yield2Print('in F (), 3')    yield3g=f ()Print(g)#output: <generator object F at 0x056f8210>Print(g.__next__())#output: In F (), 11Print(g.__next__())#output: In F (), 22Print(g.__next__())#output: In F (), 33Print(g.__next__())#Output: Stopiteration

C, the Generator object is also an iterative object, that is, it can be placed in the for loop after the in, then the generator object implements the __iter__ () method, returns itself;

 for inch g:     Print (x)
# output: In F (), 1      1 in       f (), 2      2 in       F (), 3      3

D, the Generator object implements the iterator interface (__next__ ()), and implements an iterative interface (__ITER__ ()), which returns itself;

Print (g.__iter__ is g)

# Output True

Python: Generator function