Docorator Disected

[Ron_Adam]

I was having some difficulty figuring out just what was going on with
decorators.  So after a considerable amount of experimenting I was
able to take one apart in a way.  It required me to take a closer look
at function def's and call's, which is something I tend to take for
granted.

I'm not sure this is 100%, or if there are other ways to view it, but
it seems to make sense when viewed this way.

Is there a way to do this same thing in a more direct way?  Like
taking values off the function stack directly.  How much of it get's
optimized out by the compiler?


#
#   Follow the numbers starting with zero.
#

# (0) Read defined functions into memory

def decorator(d_arg):     # (7) Get 'Goodbye' off stack
    
    def get_function(function): # (8) Get func object off stack
        
        def wrapper(f_arg):        # (9) Get 'Hello' off stack
            
            new_arg = f_arg+'-'+d_arg
            result = function(new_arg)  # (10) Put new_arg on stack
                                        # (11) Call func object
                                        
            return result          # (14) Return result to wrapper
        
        return wrapper        # (15) Return result to get_function
    
    return get_function    # (16) Return result to caller of func



@decorator('Goodbye')   # (5) Put 'Goodbye' on stack
                        # (6) Do decorator 

def func(s):            # (12) Get new_arg off stack

    return s            # (13) Return s to result

# (1) Done Reading definitions


print func('Hello')     # (2) Put 'Hello' on stack
                        # (3) Put func object on stack
                        # (4) Do @decorator
                        # (17) print 'Hello-Goodbye'

# Hello-Goodbye