Blinker demo

blinker_demo.py

# The only import needed
from blinker import signal

# Signals definition
number_generator_number = signal('number_generator_number', doc='Return a generated number')
number_generator_start = signal('number_generator_start', doc='The number generator has started')
number_generator_end = signal('number_generator_end', doc='The number generator has ended')

class NumberGenerator():
    """A dumb number generator"""
    
    def __init__(self, name, bound):
      self.name = name
      self.bound = bound
      self.counter = 0

    def generate(self):
        # Sending a simple signal
        number_generator_start.send(self)
        while self.counter < self.bound:
            # Sending a signal with an associated data (the number generated)
            number_generator_number.send(self, number=self.counter)
            yield self.counter
            self.counter += 1
        # Informing that the generation has ended
        number_generator_end.send(self)
    
    def __repr__(self):
        return self.name

# Connecting with a decorator a different method for the each signal
@number_generator_start.connect
def start_generation(sender):
    print('{sender} started'.format(sender=sender))

@number_generator_number.connect
def print_number(sender, number):
    print('Got [{number}] from {sender}'.format(number=number, sender=sender))

@number_generator_end.connect
def end_generation(sender):
    print('{sender} ended'.format(sender=sender))

# Creating a generator
number_generator = NumberGenerator('Simple Generator', 5)

# Summing values
print('Sum is {result}'.format(result=sum(number_generator.generate())))