[Python-Dev] Re: metaclass and author are already decorators (original) (raw)

Paul Morrow pm_mon at yahoo.com
Sun Aug 22 00:54:28 CEST 2004

Bob Ippolito wrote:

On Aug 21, 2004, at 6:24 PM, Paul Morrow wrote:

It seems that writing a decorator is going to be a bizarre experience. In the example, I would need to write a function named 'decoration' that returns a function that will recieve a function (foo) to be decorated and then return a function. Does that sound about right? Yes that is correct. What would functions like 'decoration' typically look like? Could you show a short code snippet? http://python.org/peps/pep-0318.html

Thanks. Of the 5 examples there, the first two are apparently not implemented correctly, as they expect that the function/class to be decorated is passed directly to them, rather than to the function they return. Would you agree? I pasted them here for your consideration...

1. Define a function to be executed at exit. Note that the function

isn't actually "wrapped" in the usual sense.

def onexit(f): import atexit atexit.register(f) return f

@onexit def func(): ...

2. Define a class with a singleton instance. Note that once the

class disappears enterprising programmers would have to be more creative to create more instances. (From Shane Hathaway on python-dev.)

def singleton(cls): instances = {} def getinstance(): if cls not in instances: instances[cls] = cls() return instances[cls] return getinstance

@singleton class MyClass: ...

More information about the Python-Dev mailing list