How to update a variable from a text file in python3

Question

So, let's say that I got a shell script that generates a v.py on the output that contains

v = some-float

And I'm accessing it in the main.py script via from v import v But later the main Script toggles generation process again and the variable in v.py gets updated, but the variable v is not updating for the main script.

To make main script work I need to update the variable from v.py while script is running

I've tried importlib.reload(v) - didn't work

I'm still new to python and don't understand it completely

You might want to lookup on how to read from and write to text file in Python — Andreas
– Andreas, Commented Dec 7, 2018 at 6:41
You could rely on v.v instead of v. In this case, importlib.reload allows for the value of v.v to change. — hilberts_drinking_problem
– hilberts_drinking_problem, Commented Dec 7, 2018 at 6:45

Luv · Accepted Answer · 2018-12-07 06:48:59Z

1

Presuming you are using python 3.*, v needs to be a module, so the way you import it changes to example below.

import v
import importlib

print(v.v)

with open('v.py', 'w') as f:
    f.write('v = 20.0')

importlib.reload(v)
print(v.v)

Also note the document of importlib

"When a module is reloaded, its dictionary (containing the module’s global variables) is retained. Redefinitions of names will override the old definitions, so this is generally not a problem."

Though our minimal example works, this is something to bear in mind for more complicated cases.

answered Dec 7, 2018 at 6:48

Luv

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