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globals() scope inside a function

I have a question regarding globals() in python

My sample code

b=9
def a1():
 'kkk'

a1()
print globals()

I got output b as global

Since b is global, I am expecting I can modify it anywhere So I modified my code to

b=9
def a1():
 'kkk'
 b=100
a1()
print globals()

still my globals() says b as 100. Why b inside the function is taken as local value while my globals() says its global?

Note: If I add keyword global b inside the function, it get convert to global. My question is why b was not getting modified inside the function while globals() declare b as global ?

Solution

  • Refer Python docs for more information. Copying the text in case URL doesn't work

    In Python, variables that are only referenced inside a function are implicitly global. If a variable is assigned a value anywhere within the function’s body, it’s assumed to be a local unless explicitly declared as global.

    Though a bit surprising at first, a moment’s consideration explains this. On one hand, requiring global for assigned variables provides a bar against unintended side-effects. On the other hand, if global was required for all global references, you’d be using global all the time. You’d have to declare as global every reference to a built-in function or to a component of an imported module. This clutter would defeat the usefulness of the global declaration for identifying side-effects.