[pyhon] Object Oriented Programming(2)

Class design

Here, let's design our own class and defined object methods.

First example (2D point class)

This class will require a constructor (to be able to create instances of the class

couple of accessors that get the x, y coordinate of the point

mutator to move the point by a certain distance

import math

class Point(object):

	def __init__(self, x, y):
    	"""Construct a point object based on (x, y) coordinates.
	Parameters:
	x (float): x coordinate in a 2D cartesian grid. y (float): y coordinate in a 2D cartesian grid.
	"""
    
    	    self._x = x
            self._y = y
      	
        def x_cord(self):
            """
            returns current x position of an object
            """
            return self.x
            
        def y_cord(self):
            """
            returns current y position of an object
            """
            return self.y
        
        def move(self, dx, dy):
            """
            moves current position to new given x, y coordinate position
            
            Parameters:
                dx(int): new x coordinate
                dy(int): new y coordinate
            """
            
            self.x += dx
            self.y += dy

Class definition starts with keyword class, followed by class name and (object):

here, note the functions that are declared inside the class block.

they are the method definition for the class

Basic definition syntax

class Classname(object):
    """comment"""
    def method_1(self, [args]):
        method_1 body
    
    def method_2(self, [args]):
        method_2 body
    
    def method_3(self, [args]):
        method_3 body

Creates a class called classname to represent the ADT specified. The methods of the class are , method_1 , method_2 and so on.

Using object method

p = Point(2, -3)

p.x_cord()
>> 2

p. y_cord()
>> -3

--------------------------------------
p.move(1, 2)

p.x_cord()
>> 3

p.y_cord()
>> -1