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POLearn Python the Hard Way 2nd Edition. Exercise 45
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  1. POLearn Python the Hard Way 2nd Edition. Exercise 45
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    copied!<p>I'm going through Learn Python the Hard Way 2nd Edition and I've just done the exercise where am suppose to write down the is-a/has-a relationships. Am able to use classes somehow but i find is-a/has-a confusing. So I have no ideas if what I've done is correct, any pointers will be appreciated. Thanks.</p> <pre><code>## Animal is-a object (yes, sort of confusing) look at the extra credit class Animal(object): pass ## ?? Dog is-a object class Dog(Animal): def __init__(self, name): ## ?? Dog has-a name self.name = name ## ?? Cat is-a object class Cat(Animal): def __init__(self, name): ## ?? Cat has-a name self.name = name class Person(object): def __init__(self, name): ## ?? Person has-a name self.name = name ## Person has-a pet of some kind self.pet = None ## ?? Employee is-a object class Employee(Person): def __init__(self, name, salary): ## ?? hmm what is this strange magic? super(Employee, self).__init__(name) ## ?? Employee has-a salary self.salary = salary ## ?? Fish is-a object class Fish(object): pass ## ?? Salmon is-a object, type of a fish class Salmon(Fish): pass ## ?? Halibut is-a object, type of a fish class Halibut(Fish): pass ## rover is-a Dog rover = Dog("Rover") ## ?? satan is-a Cat satan = Cat("Satan") ## ?? mary is-a person mary = Person("Mary") ## ?? mary has-a pet called satan mary.pet = satan ## ?? frank is-a Employee on 120000 salary frank = Employee("Frank", 120000) ## ?? frank has-a pet called rover frank.pet = rover ## ?? flipper is Fish flipper = Fish() ## ?? crouse is-a Salmon crouse = Salmon() ## ?? harry is-a Halibut harry = Halibut() </code></pre>
 

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