Python classes and objects tutorial

Python is a object oriented programming language, it supports class and objects.

1. class name should start with first letter as caps.
2. variables inside a class are called as attributes.
3. function inside a class are called as methods.
4. self keyword is used to refer the attributes and methods that belongs to the class, using the self we can directly access the attribute and method inside the class.

simple class syntax:

class Myclass():
   pass

Class constructor

class Myclass():
   def __init__(self):
      pass

init is a special method in python which as a constructor, it will be called when declaring an object.

Declaring a class object

class Myclass():
   def __init__(self):
      print("I'm Constructor")

myObject = Myclass()

Output:
I'm Constructor

by default constructor method get called, we are not directly calling any method in the class.

Passing value to constructor

class Myclass():
   def __init__(self, x, y):
      print("I'm Constructor")
      print("x:", x)
      print("y:", y)

myObject = Myclass(5, 10)

Output:
I'm Constructor
x: 5
y: 10

Assign value to class attributes

class Myclass():
   def __init__(self, x, y):
      self.x = x
      self.y = y

myObject = Myclass(5, 10)

even thought the argument x and self.x looks same but they are different, self is used to refer the attribute belong to the class, argument x is only accessible inside the init block.

Class Methods

class Myclass():
   def __init__(self, x, y):
      self.x = x
      self.y = y

   def access(self):
       print("x:", self.x)
       print("y:", self.y)

myObject = Myclass(5, 10)
myObject.access()

Output:
x: 5
y: 10

value for x and y are assigned in the constructor function even though it can be accessed anywhere inside the class since it belong to the class.

Create multiple class objects

class Myclass():
   def __init__(self, x, y):
      self.x = x
      self.y = y

   def access(self):
       print("x:", self.x)
       print("y:", self.y)

myObject1 = Myclass(5, 10)
myObject1.access()

myObject2 = Myclass(20, 30)
myObject2.access()

Output:
x: 5
y: 10
x: 20
y: 30

Consider the objects as storage space, any action made to the object only belongs to it, it won't affects other objects.

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