How can I tell whether a variable is global or local?

Question

How can I tell whether a variable in Python is global or local?

Can you say more about exactly what you're doing? It's rather unusual to need to be able to tell whether a variable is local or global, and there might well be a better way to solve whatever issue you're facing. — Mark Dickinson, Jan 29 '17 at 20:57
Well, for one, if it's not in `globals()`, then it's definitely not global. — the_constant, Jan 29 '17 at 21:03
Hi, I need to know whether the variables are global or local because the task I'm doing requires documentation and so I need to record a number of things. I'm making a treasure hunt game and have created multiple subroutines to account for the user choosing the grid size, inputting their movements etc. In the choosing grid size subroutine, I've used a variable called 'choice' but have also used this in the main s/r to account for what choice is made at main menu. In this case, is the variable global since it is used multiple times for different processes, or local? — Ellie, Jan 29 '17 at 21:06
@Ellie As long as you didn't used `global choice` in your function / subroutine, the local variable will be used in the function — ovs, Jan 29 '17 at 21:18
Now you know why global variables are generally frowned upon. The easiest way to keep track if you must use them is to use a naming convention. — Mark Tolonen, Jan 29 '17 at 21:21

score 3 · Answer 1 · edited May 23 '17 at 12:16

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globals() will return a dict of global variables

locals() will return a dict of local variables

to check if the scope of the variable:

if 'variable' in locals(): print("It's local") #Replace 'variable' with the variable
elif 'variable' in globals(): print("It's global") #But keep the quotation marks
else: print("It's not defined")

If you don't know about scopes, heres a good page to go to https://stackoverflow.com/a/292502/7486769

edited May 23 '17 at 12:16

Community

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answered Jan 29 '17 at 21:08

kda

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Hi, how do I use this exactly to check? Please bear with me because I'm only a student and don't have a great deal of complex understanding in terms of python. If I just paste this at the bottom of my code will it output the variables that are global/ local? – Ellie Jan 29 '17 at 21:12
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I would change the order of `var in globals()` and `var in locals()`. When a var is in `locals` and in `globals` the local variable will be used. – ovs Jan 29 '17 at 21:13
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BTW `globals()` and `locals()` returns `dict` not `list` – Moinuddin Quadri Jan 29 '17 at 21:22

score 0 · Answer 2 · answered Jan 29 '17 at 21:11

If all you are doing is making a list for some documentation, all you need to do is create a list of variables that are defined outside of any function or class.

var1 = "something"

def foo():
    var2 = "something"

In the above, var1 is global, var2 is local.

How can I tell whether a variable is global or local?

2 Answers2