An example of using the contextlib ContextDecorator class to create a class that can be used as a decorator or a context manager

Context Decorator.py

import time

from contextlib import ContextDecorator



class Logger(ContextDecorator):
    """
    Logger()
    
    Logger can be used as both a decorator or as a context manager.
    
    Examples:
        As a decorator:
        
        import logger

        @logger
        def somefunc():
            return "hello world!"

        As a context manager:
        
        import logger
        
        def somefunc():
            with logger:
                print("context managed!")
    """
    def __enter__(self):
        self.start = time.time()
        return self
        
    def __exit__(self, exc_type, exc_val, exc_tb):
        print("runtime: {}".format(time.time() - self.start))
        return False
        
logger = Logger()