Scope of Functions as objects in Python

Question

I am trying to understand how python stores and accesses its functions as objects . For example take the following code-

def make_pretty(func):
    def inner():
        print("I got decorated")
        func()
        return func
    return inner

def ordinary():
    print("I am ordinary 2")

ordinary()
pretty=make_pretty(ordinary)

pretty()

When executed , pretty() returns

I got decorated
I am ordinary 2
<function __main__.ordinary()>

which seems to imply that the ordinary() function passed to make_pretty() is accessed as in the main scope, and as dir(pretty) doesn't show ordinary (Please correct me if i am wrong). Now if I run this code after this

def ordinary():
    print("I am ordinary 3")

pretty()

I still get the same output as before , even though I have the changed the global definition of ordinary , i.e. pretty still is considering the previous definition of ordinary even though I have redefined ordinary and the func in pretty is referring to global ordinary

Why is this so? I clearly am wrong somewhere but I don't understand where. Some insight would be appreciated. Thanks

I read about object references from python-course.eu/passing_arguments.php , from what I understand in this case , ordinary is called by reference until it is changed , and when it is changed it becomes call by value . is this correct ? — Niteya Shah
– Niteya Shah, Commented Aug 18, 2018 at 19:42

mkrieger1 · Accepted Answer · 2018-08-18 19:46:15Z

1

even though I have the changed the global definition of ordinary , i.e. pretty still is considering the previous definition of ordinary even though I have redefined ordinary and the func in pretty is referring to global ordinary

You didn't change the function object that pretty refers to. You created a new function, and gave the name ordinary to it. The original function still exists, but can no longer be referred to by the name ordinary.

pretty doesn't know about all this. It refers to the original function all the time.

Before

Both the name "ordinary" and the function pretty refer to the same function:

<function 1>  <-- "ordinary"
              <-- pretty

After

The name "ordinary" refers to a new function, but pretty still refers to the original function:

<function 1>  <-- pretty

                "ordinary" -->  <function 2>

answered Aug 18, 2018 at 19:46

mkrieger1

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1 Comment

Niteya Shah Over a year ago

Yeah understood that after using id for the function , thanks anyway

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