design-patterns-for-humans/Python/Behavioral/Observer.py at d8bca1cbcb9250b7bbdf12eaa876bd08fc1751c7 · nilbuild/design-patterns-for-humans · GitHub

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class JobPost:
    _title = None

    def __init__(self, title):
        self.title = title

    def getTitle(self):
        return self.title

class JobSeeker:
    _name = None

    def __init__(self, name):
        self.name = name

    def onJobPosted(self, job):
        print 'Hi ' + self.name + '! New job posted: ' + job.getTitle()

class EmploymentAgency:
    _observers = []

    def notify(self, jobPosting):
        for observer in self._observers:
            observer.onJobPosted(jobPosting)

    def attach(self, observer):
        self._observers.append(observer)

    def addJob(self, jobPosting):
        self.notify(jobPosting)


johnDoe = JobSeeker('John Doe')
janeDoe = JobSeeker('Jane Doe')

jobPostings = EmploymentAgency()
jobPostings.attach(janeDoe)
jobPostings.attach(johnDoe)

jobPostings.addJob(JobPost('Software Engineer'))
'''
Output
Hi John Doe! New job posted: Software Engineer
Hi Jane Doe! New job posted: Software Engineer
'''