Classes And Objects

Class Definition

Class is a blueprint in which characteristics (properties) and behaviors (functions) are defined.

An example of class definition is:

class Person: pass

In the example:

• class is the keyword for class defining.
• Person - the name of the class.
• pass is used only if the class body is empty (it avoids exception throw).

Object Creation

Object is an instance created from a class.

Using the defined class we can create objects and set properties.

class Person: def introduceYourself(self): print("I'm", self.name , "and I'm", self.age, "years old.") # create object personObject = Person() # set properties personObject.name = "John" personObject.age = 20 personObject.introduceYourself()

Output:

I'm John and I'm 20 years old.

Explanation:

• At lines 1 - 3 a class is defined.
• The class has a function introduceYourself that uses the properties of a class object via the self parameter.
• Notice that class function must always have at least 1 parameter. That's because the first argument (self) points to the class object.
• At line 6 an object is created.
• At lines 9 and 10 values are set to the properties.
• At lines 12 the function introduceYourself is called and a message is printed.