Convert dictionary entries into variables in function

Question

I want to get variables for work in function from dict.

Simple example

>>> def func(atrs):
...     for k,v in atrs.items():
...             exec(k + '=v')
...     
...     # do smth here with vars
...     
...     print(locals())   # lets see that 'a' exists
...     print(a)          # lets use 'a'

And after I use this func I get the error.

>>> func({'a':1, 'b':5})
{'atrs': {'a': 1, 'b': 5}, 'k': 'b', 'v': 5, 'a': 1, 'b': 5}
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 5, in func
NameError: name 'a' is not defined

But we can see that 'a' exists in defined variables. What I doing wrong?

I see this and it works if we dont use functions. Convert dictionary entries into variables

But I need use functions.

score 0 · Answer 1 · answered Jan 23 '22 at 12:37

0

I strongly discouraged you to use this kind of method but you can use locals() (or vars()) to create variables dynamically:

def func(attrs):
    for k, v in attrs.items():
        locals()[k] = v
    print(locals())
    print(a)
    print(b)

func({'a':1, 'b':5})

Output:

{'attrs': {'a': 1, 'b': 5}, 'k': 'b', 'v': 5, 'a': 1, 'b': 5}
1
5

If you want this variables exist out of the scope of func function, replace locals() or vars() by globals().

answered Jan 23 '22 at 12:37

Corralien

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1

No, I just get the same error: NameError: name 'a' is not defined Can it be problem with my python interpreter or smth like this? – Ivan Cheshkov Jan 23 '22 at 12:50
Do you copy/paste my code? – Corralien Jan 23 '22 at 12:51
1

Yes, I copy paste your code. https://imgur.com/3PZwMAG – Ivan Cheshkov Jan 23 '22 at 12:52
I don't understand the problem. Your code works for me! – Corralien Jan 23 '22 at 13:03

score 0 · Answer 2 · answered Jan 23 '22 at 13:25

Ok, I dont understand why, but it works if we define this vars like globals, not locals.

def func(attrs):
    for k, v in attrs.items():
        globals()[k] = v
    
    # or we can use this instead of 'for' loop
    # globals().update(attrs)
    
    print(locals())
    print(globals())
    print(a)
    print(b)

func({'a':1, 'b':5})

Output

{'attrs': {'a': 1, 'b': 5}, 'k': 'b', 'v': 5}
{'__name__': '__main__', ..., 'a': 1, 'b': 5}
1
5

Convert dictionary entries into variables in function

2 Answers2