Continuing with the articles on Object-Oriented Programming in Python, in this case we will use what was covered in part 4 of the series, where a Punto2D class was created along with a child class Punto3D that inherited from Punto2D.
In this case new concepts will be introduced:
- metaclasses (abstract class)
- abstract method:
With the abstract class, a class is defined with its abstract methods, which do nothing and only declare the methods; then that class is inherited and the methods that were defined as abstract are implemented.
In this case the abstract class ADTPunto is created, which defines a series of methods; then the class Punto is created, inheriting from ADTPunto, where the methods defined in the abstract class are implemented. The abstract class ends up being like an interface for a class.
The code of the abstract class punto is shown below:
from abc import ABCMeta, abstractmethod
class ADTPunto (object):
__metaclass__ = ABCMeta
@abstractmethod
def ValorX(self):
pass
@abstractmethod
def ValorY(self):
pass
@abstractmethod
def mover(self,puntoNuevo):
pass
@abstractmethod
def reset(self):
pass
@abstractmethod
def distanciaOtroPunto(self,punto):
pass
The Punto class that inherits from ADTPunto is shown below:
from math import sqrt
class Punto(ADTPunto):
def __init__(self,x,y):
self.__x = x
self.__y = y
super(Punto,self).__init__()
@property
def punto(self):
"""el getter de punto, devuelve el punto"""
return (self.__x,self.__y)
@punto.setter
def punto(self,Punto):
"""Asigna nuevo valor al punto"""
self.__x = Punto.punto[0]
self.__y = Punto.punto[1]
@punto.deleter
def punto(self):
"""Borra los valores del punto"""
del self.__x
del self.__y
@property
def ValorX(self):
"""Devuelve el valor de x"""
return self.__x
@property
def ValorY(self):
"""Devuelve el valor de y"""
return self.__y
def reset(self):
"""Fija el punto en (0,0)"""
self.__x = 0
self.__y = 0
def distanciaOtroPunto(self,oPunto):
'''devuelve la distancia entre el punto original y un punto dado'''
return sqrt((self.__x - oPunto.punto[0])**2 + (self.__y - oPunto.punto[1])**2 )
def mover(self,oPunto):
"""Cambia el punto a un nuevo punto"""
self.__x = oPunto.punto[0]
self.__y = oPunto.punto[1]
Finally, the instantiation of both classes is shown:
if __name__ == "__main__":
try:
prueba = ADTPunto()
except (TypeError):
print ("No puede instanciar una clase abstracta")
punto2d = Punto(3,5)
print(punto2d.punto)
print(punto2d.ValorX)
print(punto2d.ValorY)
punto2d.mover(Punto(5,5))
print(punto2d.punto)
print(punto2d.distanciaOtroPunto(Punto(10,10)))
punto2d.reset()
print(punto2d.punto)When the script is run you get the following:
python ej12_adt.py
No puede instanciar una clase abstracta
(3, 5)
3
5
(5, 5)
7.07106781187
(0, 0)As you can see, an attempt was made to instantiate the ADTPunto class, which generates a type error.
The complete code of the classes is in gitlab in the tutorial-poo repo.
Make a donation! If you liked the article you can make a donation with Bitcoin (BTC) using the digital wallet of your choice to the following address: 17MtNybhdkA9GV3UNS6BTwPcuhjXoPrSzV
Or by scanning the QR code from your wallet:
