promisesexample.py

promisesexample.py

users = []

def registerUser(username):
	global users 
	if username.isdigit():
		raise ValueError("Invalid username: {}".format(username))
	users.append(username)
	return username

def touchFileForUser(username):
	print("Creating file for {}".format(username))

def newWelcomeEmail(username):
	print("Welcome {} to company X .inc".format(username))

p1 = Promise(lambda resolve, reject: resolve(registerUser("ahmed")))
p1.then(lambda u: touchFileForUser(u))
p1.then(lambda u: print("Can we create an email too?"))


p2 = Promise(lambda resolve, reject: resolve(registerUser("dmdm")))
p2.then(touchFileForUser)
p2.then(newWelcomeEmail)

p3 = Promise(lambda resolve, reject: resolve(registerUser("30")))
p3.then(touchFileForUser)
p3.catch(lambda msg: print("ERRROR HAPPENED {}".format(msg)))
print(p1, p2, p3)
print(users)