Python - Coroutines

Coroutines

Example 1

def TokenIssuer():
    tokenId = 0
    while True:
        name = yield
        tokenId += 1
        print('Token number of', name, ':', tokenId)
t = TokenIssuer()
next(t)
t.send('George')
t.send('Rosy')
t.send('Smith')

Output

Token number of George: 1
Token number of Rosy: 2
Token number of Smith: 3

Example 2

def TokenIssuer(tokenId=0):
    try:
       while True:
            name = yield
            tokenId += 1
            print('Token number of', name, ':', tokenId)
    except GeneratorExit:
        print('Last issued Token is :', tokenId)
t = TokenIssuer(100)
next(t)
t.send('George')
t.send('Rosy')
t.send('Smith')
t.close()

Output

Token number of George: 101
Token number of Rosy: 102
Token number of Smith: 103
Last issued Token is: 103

Example 3

def coroutine_decorator(func):
    def wrapper(*args, **kwdargs):
        c = func(*args, **kwdargs)
        next(c)
        return c
    return wrapper

@coroutine_decorator
def TokenIssuer(tokenId=0):
    try:
        while True:
            name = yield
            tokenId += 1
            print('Token number of', name, ':', tokenId)
    except GeneratorExit:
        print('Last issued Token is :', tokenId)
t = TokenIssuer(100)
t.send('George')
t.send('Rosy')
t.send('Smith')
t.close()

Output

Token number of George: 101
Token number of Rosy: 102
Token number of Smith : 103
Last issued Token is : 103