Decorator experiments to see what order they get executed in and how we can pass parameters

decorator_experiments.py

#!/usr/bin/python

"""
The object here is to demonstrate the following about Python decorators:

- All decorators that execute logic prior to calling the decorated function
  executed before the decorators that execute logic after the decorated 
  function executes

- Order or application of the decorators does not break the point above

- Ensuring order of operations of pre-hook decorators

- Passing parameters to decorators
"""

from functools import wraps

def request(method):
    def request_wrapper(handler):
        wraps(handler)
        def request_parser(*args, **kwargs):
            print("PRE  >> Do my request parsing first %s" % method)
            return handler(*args, **kwargs)
        return request_parser
    return request_wrapper

def authentication(handler):
    wraps(handler)
    def response_wrapper():
        print("PRE  >> Running authentication checks")
        return handler()
    return response_wrapper

def response(handler):
    wraps(handler)
    def response_wrapper():
        handler_response = handler()
        #: This would process the response from the handler
        print("POST >> Processing response %s" % handler_response)
        return handler_response
    return response_wrapper


@response
@request(method="GET")
def handler_endpoint():
    print("MAIN >> Handler with response, request")
    return "GET Response"


@response
@authentication
@request(method="POST")
def handler_decorator_order_1():
    print("MAIN >> Handler with response, auth, request")
    return "POST Response"


@request(method="PUT")
@authentication
@response
@response
def handler_decorator_order_2():
    print("MAIN >> Handler with request, auth, response")
    return "PUT Response"

if __name__ == '__main__':
    print("Handler Test:")
    handler_endpoint()

    print("\nHandler with incorrect order:")
    handler_decorator_order_1()

    print("\nHandler with incorrect order:")
    handler_decorator_order_2()