一文系统梳理Python类的特殊方法体系

class Singleton:
    _instance = None
    def __new__(cls):
        if not cls._instance:
            cls._instance = super().__new__(cls)
        return cls._instance

class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y

class FileHandler:
    def __del__(self):
        self.file.close()

class Point:
    def __str__(self):
        return f"坐标点({self.x}, {self.y})"

class Student:
    def __repr__(self):
        return f"Student(name='{self.name}', score={self.score})"

class Money:
    def __format__(self, format_spec):
        return f"${self.amount:,{format_spec}}"

class MyList:
    def __len__(self):
        return len(self.items)

class Matrix:
    def __getitem__(self, index):
        return self.data[index[0]][index[1]]

class Fibonacci:
    def __iter__(self):
        self.a, self.b = 0, 1
        return self
    def __next__(self):
        value = self.a
        self.a, self.b = self.b, self.a + self.b
        return value

class Person:
    def __eq__(self, other):
        return self.id == other.id

class Vector:
    def __add__(self, other):
        return Vector(self.x+other.x, self.y+other.y)

class BinaryMask:
    def __and__(self, other):
        return self.value & other.value

class DatabaseConnection:
    def __enter__(self):
        self.connect()
        return self
    def __exit__(self, exc_type, exc_val, exc_tb):
        self.close()

class DynamicAttributes:
    def __getattr__(self, name):
        if name.startswith('field_'):
            return 0
        raise AttributeError

class ValidatedAttributes:
    def __setattr__(self, name, value):
        if name == 'age' and not 0 <= value <= 150:
            raise ValueError("Invalid age")
        super().__setattr__(name, value)

class Adder:
    def __call__(self, a, b):
        return a + b
adder = Adder()
print(adder(3, 5))  # 输出8

class User:
    def __hash__(self):
        return hash(self.id)
    def __bool__(self):
        return self.is_active

class Vector:
    def __init__(self, x, y):
        self.x = x
        self.y = y
    
    def __repr__(self):
        return f"Vector({self.x}, {self.y})"
    
    def __add__(self, other):
        return Vector(self.x + other.x, self.y + other.y)
    
    def __sub__(self, other):
        return Vector(self.x - other.x, self.y - other.y)
    
    def __mul__(self, scalar):
        return Vector(self.x * scalar, self.y * scalar)
    
    def __eq__(self, other):
        return self.x == other.x and self.y == other.y
    
    def __lt__(self, other):
        return self.x**2 + self.y**2 < other.x**2 + other.y**2

# 测试
v1 = Vector(3, 4)
v2 = Vector(1, 2)
print(v1 + v2)  # Vector(4, 6)
print(v1 * 2)   # Vector(6, 8)
print(v1 == v2) # False