Python3 面向objectprogrammingtutorial

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
    
    def greet(self):
        print(f"Hello, my name is {self.name} and I'm {self.age} years old.")

# creationPersonclass instance
person1 = Person("Alice", 30)
person2 = Person("Bob", 25)

# 访问object property
print(person1.name)  # 输出: Alice
print(person2.age)   # 输出: 25

# 调用object method
person1.greet()  # 输出: Hello, my name is Alice and I'm 30 years old.
person2.greet()  # 输出: Hello, my name is Bob and I'm 25 years old.

class Student(Person):
    def __init__(self, name, age, student_id):
        # 调用父class __init__method
        super().__init__(name, age)
        self.student_id = student_id
    
    def study(self):
        print(f"Student {self.name} (ID: {self.student_id}) is studying.")

# creationStudentclass instance
student = Student("Charlie", 20, "S12345")

# 访问inheritance property
print(student.name)  # 输出: Charlie
print(student.age)   # 输出: 20

# 访问自己 property
print(student.student_id)  # 输出: S12345

# 调用inheritance method
student.greet()  # 输出: Hello, my name is Charlie and I'm 20 years old.

# 调用自己 method
student.study()  # 输出: Student Charlie (ID: S12345) is studying.

class Animal:
    def speak(self):
        pass

class Dog(Animal):
    def speak(self):
        return "Woof!"

class Cat(Animal):
    def speak(self):
        return "Meow!"

class Cow(Animal):
    def speak(self):
        return "Moo!"

# polymorphism 例子
def animal_sound(animal):
    print(animal.speak())

# creation不同 动物object
dog = Dog()
cat = Cat()
cow = Cow()

# 调用相同 function, 传入不同 object
animal_sound(dog)  # 输出: Woof!
animal_sound(cat)  # 输出: Meow!
animal_sound(cow)  # 输出: Moo!

class BankAccount:
    def __init__(self, owner, balance):
        self.owner = owner  # 公共property
        self._balance = balance  # 保护property
        self.__password = "123456"  # 私 has property
    
    def deposit(self, amount):
        if amount > 0:
            self._balance += amount
            print(f"Deposit successful. New balance: {self._balance}")
        else:
            print("Deposit amount must be positive.")
    
    def withdraw(self, amount, password):
        if password != self.__password:
            print("Invalid password.")
            return
        if amount > 0 and amount <= self._balance:
            self._balance -= amount
            print(f"Withdrawal successful. New balance: {self._balance}")
        else:
            print("Invalid withdrawal amount.")
    
    def get_balance(self):
        return self._balance

# creationBankAccountobject
account = BankAccount("Alice", 1000)

# 访问公共property
print(account.owner)  # 输出: Alice

# 尝试访问保护property (不推荐) 
print(account._balance)  # 输出: 1000

# 尝试访问私 has property (会报错) 
# print(account.__password)  # AttributeError: 'BankAccount' object has no attribute '__password'

# throughmethod访问 and modifyproperty
account.deposit(500)  # 输出: Deposit successful. New balance: 1500
account.withdraw(200, "123456")  # 输出: Withdrawal successful. New balance: 1300
print(account.get_balance())  # 输出: 1300

class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y
    
    def __str__(self):
        return f"Vector({self.x}, {self.y})"
    
    def __repr__(self):
        return f"Vector({self.x}, {self.y})"
    
    def __add__(self, other):
        if isinstance(other, Vector):
            return Vector(self.x + other.x, self.y + other.y)
        return NotImplemented
    
    def __eq__(self, other):
        if isinstance(other, Vector):
            return self.x == other.x and self.y == other.y
        return False
    
    def __len__(self):
        # 返回向量  long 度 (模) 
        return int((self.x ** 2 + self.y ** 2) ** 0.5)

# usingVectorclass
v1 = Vector(3, 4)
v2 = Vector(1, 2)

# using__str__method
print(v1)  # 输出: Vector(3, 4)

# using__add__method
v3 = v1 + v2
print(v3)  # 输出: Vector(4, 6)

# using__eq__method
print(v1 == v2)  # 输出: False

# using__len__method
print(len(v1))  # 输出: 5