如何基于python中的特定条件将参数动态传递给decorator？

Question

I have written a timeout decorator function with the file named --- timeout.py.

from functools import wraps
import errno
import os
import signal

class TimeoutError(Exception):
    pass

def timeout(seconds=10, error_message=os.strerror(errno.ETIME)):
    def decorator(func):
        def _handle_timeout(signum, frame):
            raise TimeoutError(error_message)
        @wraps(func)
        def wrapper(*args, **kwargs):
            signal.signal(signal.SIGALRM, _handle_timeout)
            signal.alarm(seconds)
            try:
                result = func(*args, **kwargs)
            finally:
                signal.alarm(0)
            return result

        return wrapper

    return decorator

Now I have another file which has the following code in a different file

"""some code at the starting"""
if keyword == 'this_one':
    real_time_reading(this_one)    #how to send timeout_in_seconds dynamically
elif keyword == 'that_one':
    real_time_reading(this_one)

@timeout(timeout_in_seconds)
def real_time_reading(keyword):
    '''Here it does some operations and if there is no input
       it times out based on the timeout_in_seconds value given
       to decorator'''

My requirement is based on the keyword I want to send timeout_in_seconds to decorator.

Meaning, if keyword== 'this_one' then, the real_time_reading function should time out after 30 seconds and if keyword== 'that_one' then, the real_time_reading function should time out after 60 seconds

Is there a way to send decorator arguments dynamically based on certain condition?

Answer 1

No, the decorator is initialised when the function is parsed. There might be ways to dynamically alter (hack) it, but that would have undesired consequences.

I suggest using two functions:

"""some code at the starting"""
if keyword == 'this_one':
    real_time_reading_this_one(keyword)
elif keyword == 'that_one':
    real_time_reading_that_one(keyword)

@timeout(timeout_in_seconds)
def real_time_reading_this_one(keyword)
    return _real_time_reading(keyword);

@timeout(timeout_in_seconds * 2)
def real_time_reading_that_one(keyword)
    return _real_time_reading(keyword);

def _real_time_reading(keyword):
    '''Here it does some operations and if there is no input
       it times out based on the timeout_in_seconds value given
       to decorator'''