Python: All about generators

Generators are very powerful in Python. Its created using 'yield' within the function.

Here are three most important variants, where 'yield' makes a function a generator, a coroutine or  as a context manager: [Will explain each when i get time :) ]

A. Using 'Yield' as a generator in function:
def mygen(a=0, b=1): 

 while True: 

      yield b 

      a, b = b, a + b 

c = mygen() 

for i in range(10): print(c.next())

B. Using 'Yield' as co-routine:

def mycoroutine(): 

     v_count = 0 inv_count = 0
     try: 

         while True: 

                 myinput = yield
                 if isinstance(myinput, int): 

                        v_count = v_count + 1
                 else: 

                        inv_count = inv_count + 1
       except GeneratorExit: 

             print("You Sent {} valid digits and {} invalid chars:".format(v_count,inv_count)) 

 mygen = mycoroutine() 

mygen.next()

for i in range(10)+ list("Invalidchars"):
       mygen.send(i)

C. Using 'Yield' as context manager

from contextlib import contextmanager 

@contextmanager

def function_as_contxmgr(object): 

    try: 

       object.counts +=1
       yield
    finally: 

       object.counts -=1 

class MyContext: 

       def __init__(self, arg):

             self.counts = arg 

            myobj = MyContext(10) 

with function_as_contxmgr(myobj): 

       print(myobj.counts) 

print(myobj.counts)