Python：有没有办法永久更改另一个 Python 文件中的变量？

Question

Is there a way to permanently change a variable, so it does not reset when the code finishes? I have this code:

variables.py:

myvar = None

Main.py:

import variables
variables.myvar = True

Get_variable.py:

import variables
print(variables.myvar)

Output:

None

I want it to print True

Answer 1

I don't believe it's possible (without re-writing the entire python script in the second script to write the entire thing back to file), but there's another way to do this. Instead of storing variables in a python script, you can store variables in another type of file, like a json. You could have "variables.json":

{ "myvar": null }

then in your python:

import json         # import the json library

with open("variables.json", "r") as f:      # read the json file
  variables = json.load(f)

myvar = variables["myvar"]    # To get the value currently stored

variables["myvar"] = True    # change the variable in python

with open("variables.json", "w") as f:      # write back to the json file
  json.dump(variables, f)

If you have a lot of variables, you can store them all in json as with a dictionary:

{ "onevar": null,
  "twovar": "kittens",
  "redvar": "foo",
  "bluevar": "bar" }

FOR OPENOFFICE WRITER: Since you're writing all of this in OpenOffice on a Raspberry pi, and having trouble creating the json file yourself (open office assumes it's a writer document), you can simply allow python to create it:

import json

variables = { "onevar": null,
              "twovar": "kittens",
              "redvar": "foo",
             "bluevar": "bar" }

with open("variables.json", "w") as f:
  json.dump(variables, f)

If python is told to open a file to write, and the file doesn't exist, python should create the file in question, unless it's told to create it in a directory that doesn't exist (so, you couldn't say open("myfolder/variables.json", "w") if the directory "myfolder" didn't exist). You can run this once to init your json file, and then go on opening and closing from there.

Answer 2

You can change the file:

fin = open("path-to-variables.txt","a")
fin.write("myvar = True")

That should change the actual file.