Recap#

In Lesson 12, we learned about classes and objects . Here’s a quick recap of the terminology that we learned since it will be important to know these terms.

A class is a blueprint that can be used to construct instances of that blueprint. A class defines the state of the object and what behaviors it has. For example, we defined the Dog class as follows:
```
class Dog:
    def __init__(self, name):
        self.name = name

    def bark(self):
        print(self.name + ': Woof')
```
An object (or instance ) is an instantiation of a class that has its own set of fields. You can create an instance of the Dog class by using the following syntax.
```
d = Dog('Fido')
```
The state of the object is represented by its fields. A field is essentially a variable owned by that object that is around for that object’s lifetime. The Dog class has the field name .
The behavior of an object is defined by the methods written in its class. The Dog class has the method bark .
Variables store references to objects rather than the objects themselves. This means the following program has 2 Dog objects and 3 Dog references.
```
d1 = Dog('Chester')
d2 = Dog('Scout')
d3 = d1
```
A memory model is a picture that helps us see which objects exist in our program and which variables reference which objects.
__init__ is a special method used when creating an instance of the object. It determines which parameters need to be passed when you create a new instance.

Every method defined in a class needs to take a parameter self so the method can access the fields/methods of the instance the method is being called on.

d1 = Dog('Chester')
d2 = Dog('Scout')
d3 = d1
d1.bark()  # When running, self refers to Dog('Chester')
d2.bark()  # When running, self refers to Dog('Scout')
d3.bark()  # When running, self refers to Dog('Chester')

Intermediate Data Programming

Recap

Recap#