Po co jest dziedziczenie?
Kod nr 21:
class Person:
def __init__(self, name):
self.name = name
def get_name(self):
return self.name
def is_employee(self):
return False
class Employee(Person):
def is_employee(self):
return True
emp = Person("Bartek")
print(emp.get_name(), emp.is_employee())
emp = Employee("Sylwia")
print(emp.get_name(), emp.is_employee())
Klasa object jest bazowa dla wszystkich obiektów.
Kod nr 22:
class Person(object):
def __init__(self, name):
self.name = name
def get_name(self):
return self.name
def is_employee(self):
return False
class Employee(Person):
def is_employee(self):
return True
emp = Person("Bartek")
print(emp.get_name(), emp.is_employee())
emp = Employee("Sylwia")
print(emp.get_name(), emp.is_employee())
Jak zrobić konstruktor w klasie pochodnej?
Kod nr 23:
class Person:
def __init__(self, fname, lname):
self.firstname = fname
self.lastname = lname
def printname(self):
print(self.firstname, self.lastname)
class Student(Person):
def __init__(self, fname, lname):
Person.__init__(self, fname, lname)
Kod nr 24:
class Person:
def __init__(self, fname, lname):
self.firstname = fname
self.lastname = lname
def printname(self):
print(self.firstname, self.lastname)
class Student(Person):
def __init__(self, fname, lname):
super().__init__(fname, lname)
Kod nr 25:
class Person:
def __init__(self, fname, lname):
self.firstname = fname
self.lastname = lname
def printname(self):
print(self.firstname, self.lastname)
class Student(Person):
def __init__(self, fname, lname, year):
super().__init__(fname, lname)
self.graduationyear = year
def welcome(self):
print("Welcome", self.firstname, self.lastname, "to the class of", self.graduationyear)
Ćwiczenie1. Dodaj do powyższych klas więcej pól i metod i poćwicz ich wywoływanie.
Polimorfizm to inaczej “wielopostaciowość”. Innymi słowy, mechanizmy pozwalające programiście używać wartości, zmiennych i podprogramów na kilka różnych sposobów.
Jak to jest zaimplementowane w języku Python?
Ćwiczenie. Stwórz klasy dotyczące osoby, książki i zwierzęcia (z kilkoma polami) do ćwiczenia poniższych konstrukcji.
Kod nr 26:
a = 4
b = 2
c = a + b
print(c)
s1 = "abc"
s2 = "xyz"
s3 = s1 + s2
print(s3)
Kod nr 27
print(len("abcde"))
print(len([3, -2, 8, 2, 2, -2, 0]))
Kod nr 28
def sumxyz(x, y, z=0):
return x + y + z
print(sumxyz(1, 2, 3))
print(sumxyz(3, 4))
Kod nr 29
class Number:
def sum(self, a=None, b=None, c=None):
s = 0
if a is not None and b is not None and c is not None:
s = a + b + c
elif a is not None and b is not None:
s = a + b
else:
s = a
return s
x = Number()
print(x.sum(1))
print(x.sum(3, 5))
print(x.sum(1, 2, 3))Kod nr 30
class Student:
def __init__(self, m1, m2):
self.m1 = m1
self.m2 = m2
def __add__(self, other):
m1 = self.m1 + other.m1
m2 = self.m2 + other.m2
s3 = Student(m1, m2)
return s3
s1 = Student(58, 59)
s2 = Student(60, 65)
s3 = s1 + s2
print(s3.m1)Tzw “magiczne metody”
Kod nr 31
class Cat:
def __init__(self, name, age):
self.name = name
self.age = age
def info(self):
print(f"I am a cat. My name is {self.name}. I am {self.age} years old.")
def make_sound(self):
print("Meow")
class Dog:
def __init__(self, name, age):
self.name = name
self.age = age
def info(self):
print(f"I am a dog. My name is {self.name}. I am {self.age} years old.")
def make_sound(self):
print("Bark")
cat1 = Cat("Kitty", 2.5)
dog1 = Dog("Fluffy", 4)
animals = [cat1, dog1]
for animal in animals:
animal.make_sound()
animal.info()
animal.make_sound()
Kod nr 32
from math import pi
class Shape:
def __init__(self, name):
self.name = name
def area(self):
pass
def fact(self):
return "I am a two-dimensional shape."
def __str__(self):
return self.name
class Square(Shape):
def __init__(self, length):
super().__init__("Square")
self.length = length
def area(self):
return self.length ** 2
def fact(self):
return "Squares have each angle equal to 90 degrees."
class Circle(Shape):
def __init__(self, radius):
super().__init__("Circle")
self.radius = radius
def area(self):
return pi * self.radius ** 2
figures = [Shape("Nazwa"), Circle(2), Square(3)]
for f in figures:
print(f.area())
Kod nr 33
import math
class Point:
name = "W"
def __init__(self, a, b):
self.x = a
self.y = b
def move(self, mx, my):
self.x += mx
self.y += my
def dist(self, other=None):
if other is None:
return math.sqrt(self.x ** 2 + self.y ** 2)
else:
return math.sqrt((self.x - other.x) ** 2 + (self.y - other.y) ** 2)
p1 = Point(2, 2)
p1.name = "A"
p1.move(-1, 1)
p2 = Point(3, 4)
p3 = Point(2, 0)
p1.name = "R"
Point.name = "T"
p3.name = "g"
Point.name = "v"Kod nr 34
from datetime import date
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
@classmethod
def frombirthyear(cls, name, year):
return cls(name, date.today().year - year)
@staticmethod
def isadult(age):
return age > 18
person1 = Person('mayank', 21)
person2 = Person.frombirthyear('mayank', 1996)
print(person1.age)
print(person2.age)
print(Person.isadult(22))Kod nr 35:
class Student:
name = 'unknown' # class attribute
def __init__(self):
self.age = 20 # instance attribute
@classmethod
def tostring(cls):
print('Student Class Attributes: name=', cls.name)
Student.tostring()
s1 = Student()
s1.tostring()
s1.name = "Tom"
s1.tostring()
Kod nr 36:
class Student:
name = 'unknown' # class attribute
def __init__(self):
self.age = 20 # instance attribute
@classmethod
def tostring(cls):
print('Student Class Attributes: name=', cls.name, ', age=', cls.age)
# Student.tostring()
s1 = Student()
# s1.tostring()
s1.name = "Tom"
# s1.tostring()
Kod nr 37
class Employee:
def __init__(self, name, dept, salary):
self.name = name
self.dept = dept
self.salary = salary
def __repr__(self):
return '{' + self.name + ', ' + self.dept + ', ' + str(self.salary) + '}'
workres = [
Employee('James', 'Finance', 80000),
Employee('Robert', 'Construction', 60000),
Employee('James', 'Telecom', 70000)
]
# 1. Sort by only `dept` attribute
workres.sort(key=lambda x: x.dept)
# [{Robert, Construction, 60000}, {James, Finance, 80000}, {James, Telecom, 70000}]
print(workres)
# 2. Sort by `name` attribute, followed by `dept` attribute
workres.sort(key=lambda x: (x.name, x.dept))
# [{James, Finance, 80000}, {James, Telecom, 70000}, {Robert, Construction, 60000}]
print(workres)
# 3. Sort by `name` attribute in reverse order,
# , followed by `dept` attribute in reverse order
workres.sort(key=lambda x: (x.name, x.dept), reverse=True)
# [{Robert, Construction, 60000}, {James, Telecom, 70000}, {James, Finance, 80000}]
print(workres)
# 4. Sort by `name` attribute in the natural order,
# , followed by numeric `salary` attribute in reverse order
workres.sort(key=lambda x: (x.name, -x.salary))
# [{James, Finance, 80000}, {James, Telecom, 70000}, {Robert, Construction, 60000}]
print(workres)Kod nr 38
from operator import attrgetter
class Employee:
def __init__(self, name, dept):
self.name = name
self.dept = dept
def __repr__(self):
return '{' + self.name + ', ' + self.dept + '}'
workers = [
Employee('James', 'Telecom'),
Employee('Robert', 'Construction'),
Employee('James', 'Finance')
]
# sort by `name` and `dept` attribute
workers.sort(key=attrgetter('name', 'dept'))
# [{James, Finance}, {James, Telecom}, {Robert, Construction}]
print(workers)Kod nr 39
class Employee:
def __init__(self, name, dept):
self.name = name
self.dept = dept
def __repr__(self):
return '{' + self.name + ', ' + self.dept + '}'
workers = [
Employee('James', 'Telecom'),
Employee('Robert', 'Construction'),
Employee('James', 'Finance')
]
# sort by `name` and `dept` attribute
sortByNameAndDept = sorted(workers, key=lambda x: (x.name, x.dept))
# [{James, Finance}, {James, Telecom}, {Robert, Construction}]
print(sortByNameAndDept)Kod nr 40
class Person(object):
def __init__(self, firstname, lastname):
self.first = firstname
self.last = lastname
def __eq__(self, other):
return ((self.last, self.first) == (other.last, other.first))
def __ne__(self, other):
return ((self.last, self.first) != (other.last, other.first))
def __lt__(self, other):
return ((self.last, self.first) < (other.last, other.first))
def __le__(self, other):
return ((self.last, self.first) <= (other.last, other.first))
def __gt__(self, other):
return ((self.last, self.first) > (other.last, other.first))
def __ge__(self, other):
return ((self.last, self.first) >= (other.last, other.first))
def __repr__(self):
return "%s %s" % (self.first, self.last)
| Operator | Metoda |
|---|---|
== |
__eq__ |
!= |
__ne__ |
< |
__lt__ |
<= |
__le__ |
> |
__gt__ |
>= |
__ge__ |
Ćwiczenia. Stwórz listę osób, książek, filmów itp i posortują ją różnymi sposobami.