Object-Oriented Programming (oop)

II. Basic Use

1. Definition class

class ClassName(object):
    pass

1. Create an instance

Instance name = ClassName()

1. Use member attributes or member methods

ClassName. Attribute
 ClassName. Method name ()

3. Member modifiers

Fourth, three characteristics of object-oriented

1. Packaging

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
 
    def eat(self, food):
        print("Ate{}".format(food))
 
a = Person('jack', 10, 'male')
a.eat()

2. Inheritance

class Animal:
    def eat(self):
        print "%s eat " %self.name
 
class Cat(Animal):
    def __init__(self, name):
        self.name = name
 
class Dog(Animal):
    def __init__(self, name):
        self.name = name

c1 = Cat('cat')
c1.eat()

d1 = Dog('Dog')
d1.eat()

3. Polymorphism

class Animal(object):
	def __init__(self, name, age):
		self.name = name
		self.age = age

	def speak(self):
		pass


class Cat(Animal):
	def __init__(self, name, age):
		super().__init__(name, age)

	def speak(self):
		print("cat")


class Dog(Animal):
	def __init__(self, name, age):
		super().__init__(name, age)

	def speak(self):
		print("Wang Wang Wang")


def speak(animal):
	animal.speak()


if __name__ == '__main__':
	dog = Dog("dog", 12)
	cat = Cat("cat", 10)

	speak(dog)
	speak(cat)

V. Various methods

1. Static method

Decorator uses @static method
If no decorator is written, the class name is called intelligently. Method name (), object name can not be used. Method name ()

Call:

1. Class name. Method name ()
2. Object name. Method name ()

Feature: Class and member attributes cannot be used

class Person(object):
    def __init__(self, name):
        self.name = name
 
    @staticmethod  # Turn eat method into static method
    def eat(x):
        print("%s is eating" % x)
 
 
d = Person("xiaoming")
d.eat("jack")   

2. Class Method

Decorator uses @class method

Call: Class name. Method name ()

Feature: Only class attributes can be used

class Person(object):
	count = 0

	def __new__(cls, *args, **kwargs):
		cls.count += 1

	@classmethod  # Change eat method into class method
	def show_count(cls):
		print("Created{}Objects".format(cls.count))


d = Person()
Person.show_count()

3. Attribute Method

Decorator

• Decorated by @ attribute name. setter is the way to set attribute values.
• The method decorated by @property is the method to get the attribute value, and the name of the decorated method is used as the attribute name.
• Decorated by @ attribute name. deleter is the way to delete attribute values

Call: Object name. Property name

Feature: By turning a method into a static attribute, attributes are not called in parentheses.

class Person(object):
	def __init__(self, name):
		self.name = name
		self.__age = 0

	@property
	def age(self):
		return self.__age

	@age.setter
	def age(self, age):
		if age > 0 and age <= 100:
			self.__age = age

	@age.deleter
	def age(self):
		print("age Cannot be deleted")


p = Person("Tom")
p.age = 18
print(p.age)
del p.age

4. Magic Method

Comparison operator

Arithmetic operator