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Learn Python: Classes
Instance Variables

We’ve learned so far that a class is a schematic for a data type and an object is an instance of a class, but why is there such a strong need to differentiate the two if each object can only have the methods and class variables the class has? This is because each instance of a class can hold different kinds of data.

The data held by an object is referred to as an instance variable. Instance variables aren’t shared by all instances of a class — they are variables that are specific to the object they are attached to.

Let’s say that we have the following class definition:

class FakeDict: pass

We can instantiate two different objects from this class, fake_dict1 and fake_dict2, and assign instance variables to these objects using the same attribute notation that was used for accessing class variables.

fake_dict1 = FakeDict() fake_dict2 = FakeDict() fake_dict1.fake_key = "This works!" fake_dict2.fake_key = "This too!" # Let's join the two strings together! working_string = "{} {}".format(fake_dict1.fake_key, fake_dict2.fake_key) print(working_string) # prints "This works! This too!"

Instructions

1.

In script.py we have defined a Store class. Create two objects from this store class, named alternative_rocks and isabelles_ices.

2.

Give them both instance attributes called store_name. Set alternative_rocks‘s store_name to "Alternative Rocks". Set isabelles_ices‘s store_name to "Isabelle's Ices".

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