Python 装饰器 wraps保留函数的元信息

环境信息

• ModelArts
  • Notebook - pytorch1.4-cuda10.1-cudnn7-ubuntu18.04
    • JupyterLab - Notebook - Conda-python3

装饰器 wraps保留函数的元信息

from functools import wraps

def func_old(f):
    def inner(*args,**kwargs):
        print("start")
        f(*args,**kwargs)
        print("end")
    return inner

def func_new(f):
    @wraps(f)
    def inner(*args,**kwargs):
        print("start")
        f(*args,**kwargs)
        print("end")
    return inner

@func_old
def say_hello():
    """
    函数say_hello的说明文档
    """
    print("hello")

say_hello()

start
hello
end

# 函数say_hello的元信息放生了改变
help(say_hello)

Help on function inner in module __main__:

inner(*args, **kwargs)

@func_new
def say_world():
    """
    函数say_world的说明文档
    """
    print("world")

say_world()

start
world
end

# @wraps(f)，保留了函数的元信息
help(say_world)

Help on function say_world in module __main__:

say_world()
    函数say_world的说明文档

# 解除装饰器 错误示范
say_hello = say_hello.__wrapped__

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-23-f9218f65494a> in <module>
      1 # 解除装饰器
----> 2 say_hello = say_hello.__wrapped__

AttributeError: 'function' object has no attribute '__wrapped__'

# 解除装饰器 
say_world = say_world.__wrapped__
say_world()

world

help

help(wraps)

Help on function wraps in module functools:

wraps(wrapped, assigned=('__module__', '__name__', '__qualname__', '__doc__', '__annotations__'), updated=('__dict__',))
    Decorator factory to apply update_wrapper() to a wrapper function
    
    Returns a decorator that invokes update_wrapper() with the decorated
    function as the wrapper argument and the arguments to wraps() as the
    remaining arguments. Default arguments are as for update_wrapper().
    This is a convenience function to simplify applying partial() to
    update_wrapper().

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