Python somo la 28: inheritance kwenye OOP
Katika somo hili utakwenda kujifunz amaana ya inheritance na sheria za kuiandika inheritance.
Inheritance in Python
Inheritance ni dhana inayoruhusu class moja (child class) kurithi sifa (properties) na tabia (methods) kutoka kwa class nyingine (parent class). Hii hurahisisha matumizi tena ya code na kuwezesha kuongeza vipengele bila kuharibu class asilia. Class inayorithiwa huitwa parent class yaani mzazi na class inayorithi huitwa child class yaani mtoto.
Vipengele Muhimu vya Inheritance:
-
Parent Class: Class inayorithisha properties na methods zake.
-
Child Class: Class inayorithi kutoka kwa parent class. Inaweza kuongeza au kurekebisha functionalities za parent class.
Aina za Inheritance:
-
Single Inheritance: Child class inarithi kutoka kwa parent class moja.
-
Multilevel Inheritance: Child class inarithi kutoka kwa parent class, ambayo nayo inarithi kutoka kwa parent mwingine.
-
Hierarchical Inheritance: Parent class moja inarithiwa na child classes nyingi.
-
Multiple Inheritance: Child class inarithi kutoka kwa parent classes zaidi ya moja.
Mfano wa Single Inheritance:
Ili kuweza kurithi kutoka kwenye parent class, tutaweka jins la class inayorithiwa wwakati kunapotengeneza child class. Mfano kama parent class ni Animal na tukataka kuandika child class tutaandika hivi Dog(Animal)
Mfano:
class Animal:
def speak(self):
print("This animal speaks.")
class Dog(Animal):
def bark(self):
print("Woof! Woof!")
# Object creation
dog = Dog()
dog.speak() # Method kutoka parent class
dog.bark() # Method ya child class
Hapa, Dog ni child class inayorithi method speak() kutoka Animal.
Mfano wa Multilevel Inheritance:
class Animal:
def speak(self):
print("This animal speaks.")
class Mammal(Animal):
def walk(self):
print("This mammal walks.")
class Dog(Mammal):
def bark(self):
print("Woof! Woof!")
# Object creation
dog = Dog()
dog.speak() # Method kutoka Animal
dog.walk() # Method kutoka Mammal
dog.bark() # Method ya Dog
Multiple Inheritance:
class Animal:
def speak(self):
print("This animal speaks.")
class Pet:
def is_pet(self):
print("This is a pet.")
class Dog(Animal, Pet):
def bark(self):
print("Woof! Woof!")
# Object creation
dog = Dog()
dog.speak() # Method kutoka Animal
dog.is_pet() # Method kutoka Pet
dog.bark() # Method ya Dog
Faida za Inheritance:
-
Matumizi Tena ya Code: Hakuna haja ya kuandika code sawa mara kwa mara.
-
Upanuzi wa Tabia: Unaweza kuongeza functionalities mpya kwenye child class bila kuharibu parent class.
-
Kuonyesha Mahusiano Halisi: Inaonyesha urithi wa kihierarkia (Hierarchical Inheritance) wa tabia za vitu halisi.
Matumizi ya "super()" Keyword:
Inatumika kwenye child class kuita methods za parent class, hasa constructor __init__.
Mfano:
class Animal:
def __init__(self, name):
self.name = name
class Dog(Animal):
def __init__(self, name, breed):
super().__init__(name) # Kuita constructor ya parent
self.breed = breed
dog = Dog("Buddy", "Golden Retriever")
print(f"{dog.name} is a {dog.breed}.")
Inheritance hutoa nguvu kubwa ya kuunda code inayoweza kutumiwa tena na inayoweza kupanuliwa kwa urahisi.
