Python函数怎样用装饰器给类方法添加功能 Python函数类方法装饰器的应用技巧​

@classmethod

@staticmethod

self

cls

import functools

def log_calls(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):
        print(f"Calling {func.__name__} with args: {args}, kwargs: {kwargs}")
        result = func(*args, **kwargs)
        print(f"{func.__name__} returned: {result}")
        return result
    return wrapper

class MyClass:
    def __init__(self, value):
        self.value = value

    @log_calls
    def my_method(self, arg1):
        return self.value + arg1

# Example usage
obj = MyClass(10)
result = obj.my_method(5) # Output will include log messages
print(result)

log_calls

my_method

functools.wraps

__name__

__doc__

def validate_input(func):
    @functools.wraps(func)
    def wrapper(self, arg):
        if not isinstance(arg, int):
            raise ValueError("Argument must be an integer")
        return func(self, arg)
    return wrapper

class MyClass:
    def __init__(self, value):
        self.value = value

    @validate_input
    def update_value(self, new_value):
        self.value = new_value

# Example usage
obj = MyClass(10)
try:
    obj.update_value("abc")  # Raises ValueError
except ValueError as e:
    print(e)

validate_input

update_value

cls

def classmethod_decorator(func):
    @functools.wraps(func)
    def wrapper(cls, *args, **kwargs):
        print(f"Calling class method {func.__name__} with cls: {cls}, args: {args}, kwargs: {kwargs}")
        result = func(cls, *args, **kwargs)
        return result
    return wrapper

class MyClass:
    @classmethod_decorator
    @classmethod
    def my_class_method(cls, arg):
        return f"Class method called with {arg}"

print(MyClass.my_class_method("test"))

@classmethod

class CallCounter:
    def __init__(self, func):
        self.func = func
        self.call_count = 0

    def __call__(self, *args, **kwargs):
        self.call_count += 1
        print(f"Call count for {self.func.__name__}: {self.call_count}")
        return self.func(*args, **kwargs)

class MyClass:
    @CallCounter
    def my_method(self):
        print("Method called")

obj = MyClass()
obj.my_method()
obj.my_method()

CallCounter

my_method