CODEWITHSUNDEEP
pythonscopenamespaces
Jonathan
Jonathan

Reputation: 507

Python Global Namespace values

I am just curious, I just recently learned that the Python built-in, global, and local namespace that the interpreter uses to reference objects is basically a Python dictionary.

I am curious as to why when the global() function is called, the dictionary prints the variable objects in a string but the objects in functions defined refer to a hardware memory address?

For example-

This script:

print("Inital global namespace:")
print(globals())

my_var = "This is a variable."

print("Updated global namespace:")
print(globals())

def my_func():
        my_var = "Is this scope nested?"

print("Updated global namespace:")
print(globals())

Outputs this:

Inital global namespace:
{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x10a483208>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': 'global_check', '__cached__': None}
Updated global namespace:
{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x10a483208>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': 'global_check', '__cached__': None, 'my_var': 'This is a variable.'}
Updated global namespace:
{'__name__': '__main__', '__doc__': None, '__package__': None, '__loader__': <_frozen_importlib_external.SourceFileLoader object at 0x10a483208>, '__spec__': None, '__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>, '__file__': 'global_check', '__cached__': None, 'my_var': 'This is a variable.', 'my_func': <function my_func at 0x10a40ce18>}

'my_var': 'This is a variable.', 'my_func': <function my_func at 0x10a40ce18>

I understand some people might think these kind of things aren't important, but if I wanted to see the object for a function would I even be able to do such a thing? Does this question make sense?

Upvotes: 2

Views: 2987

Answers (2)

bphi
bphi

Reputation: 3185

When you type my_var in your code, Python needs to know what that represents. First it checks in locals and if it doesn't find a reference it checks in globals. Now Python can evaluate your code when you write 'string' == my_var. Similarly, when you write the name of a function in your code, Python needs to know what that represents. Since the output of a function can change based on the input, Python can't store a simple value like a string to represent a function in globals. Instead it stores the memory reference so that when you type my_func(), it can go to that memory store and use the function to compute the output.

Upvotes: 2

Null
Null

Reputation: 36

use global my_var Then you can assign your global variables in local namespaces

Upvotes: 0

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