1. Python装饰器
装饰器简介
装饰器是一种函数，用于修改其他函数的行为。它们允许在调用函数之前或之后执行某些代码，而无需修改函数本身。
装饰器的基本用法
def my_decorator(func):
def wrapper():
print("Something is happening before the function is called.")
func()
print("Something is happening after the function is called.")
return wrapper
@my_decorator
def say_hello():
print("Hello!")
say_hello()装饰器的高级用法
装饰器链
def decorator_one(func):
def wrapper():
print("Decorator One - Before")
func()
print("Decorator One - After")
return wrapper
def decorator_two(func):
def wrapper():
print("Decorator Two - Before")
func()
print("Decorator Two - After")
return wrapper
@decorator_one
@decorator_two
def say_hello():
print("Hello!")
say_hello()带参数的装饰器
def parametrized_decorator(param):
def real_decorator(func):
def wrapper(*args, **kwargs):
print(f"Decorator parameter: {param}")
func(*args, **kwargs)
return wrapper
return real_decorator
@parametrized_decorator("Custom Param")
def greet(name):
print(f"Hello, {name}!")
greet("Alice")2. 类方法扩展
类方法简介
类方法是属于类而不是实例的方法，通过@classmethod装饰器声明。它们允许对类本身执行操作，而不是对实例执行操作。
扩展类方法的常用方式
class MyClass:
@classmethod
def my_class_method(cls):
print("This is a class method.")
def extend_class_method(func):
def wrapper():
print("Do something before executing the method.")
func()
print("Do something after executing the method.")
return wrapper
# Applying decorator to a class method
MyClass.my_class_method = extend_class_method(MyClass.my_class_method)扩展类方法的常用方式
对类方法应用装饰器
class MyClass:
@classmethod
def my_class_method(cls):
print("This is a class method.")
def extend_class_method(func):
def wrapper():
print("Do something before executing the method.")
func()
print("Do something after executing the method.")
return wrapper
# Applying decorator to a class method
MyClass.my_class_method = extend_class_method(MyClass.my_class_method)
MyClass.my_class_method()3. 元类管理实例
元类简介
元类是类的类，用于控制类的创建。它允许在定义类时定制类的行为。
元类用于管理类的行为
class Meta(type):
def __new__(cls, name, bases, dct):
# Modify or enhance class behavior before it's created
return super().__new__(cls, name, bases, dct)
class MyClass(metaclass=Meta):
def my_method(self):
print("This is a method inside MyClass.")总结
本文介绍了Python装饰器、类方法扩展和元类的基本概念。装饰器可用于在函数执行前后添加功能。类方法扩展允许对类方法的行为进行定制。元类提供了对类的创建过程进行定制的能力。深入理解这些概念可以更好地理解Python中的高级编程技术。
