Execute a string in Python inside a function so that the variables defined can be used

Question

Given a string (e.g. "lista=[1,2,3]") I would like to be able to use the variable lista.

exec() does the work outside a function, but when used inside a function the variables cannot be used in that same function. I guess it has something to do with local and global variables but I don't really understand the problem.

For example,

def funcion(texto):
    exec(texto)
    print(lista)

funcion("lista = [3,4,5]")

Gives the error: NameError: name 'lista' is not defined.

More help on exec [here](https://blog.finxter.com/python-exec/). But, I would try to avoid using it entirely, if possible. It's risky to execute arbitrary code. — jarmod, Jul 20 '21 at 16:28
*Are you sure you really need `exec`?* What, exactly, are you actually trying to accomplish. — juanpa.arrivillaga, Jul 20 '21 at 18:04
Given a string (e.g. ´"lista=[1,2,3]"´) I would like to be able to use the variable ´lista´. — Tereso del Río Almajano, Jul 22 '21 at 00:57

score 0 · Answer 1 · answered Jul 20 '21 at 16:23

0

add globals

def funcion(texto):
    exec(texto, globals())
    print(lista)

funcion("lista = [3,4,5]")

answered Jul 20 '21 at 16:23

It_is_Chris

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Using `globals` will overwrite a variable `lista` in the global scope. There might be a reason why this should be in a function. – Matthias Jul 20 '21 at 16:28
Thank you both! And do by any chance know a way of solving the problem without adding that to the set of global variables? – Tereso del Río Almajano Jul 20 '21 at 16:43

Execute a string in Python inside a function so that the variables defined can be used

1 Answers1