在文件之间使用全局变量? [英] Using global variables between files?

问题描述

我对全局变量的工作方式有点困惑.我有一个大项目，大约有 50 个文件，我需要为所有这些文件定义全局变量.

I'm bit confused about how the global variables work. I have a large project, with around 50 files, and I need to define global variables for all those files.

我所做的是在我的项目 main.py 文件中定义它们，如下所示:

What I did was define them in my projects main.py file, as following:

# ../myproject/main.py

# Define global myList
global myList
myList = []

# Imports
import subfile

# Do something
subfile.stuff()
print(myList[0])

我试图在 subfile.py 中使用 myList，如下

I'm trying to use myList in subfile.py, as following

# ../myproject/subfile.py

# Save "hey" into myList
def stuff():
    globals()["myList"].append("hey")

我尝试过的另一种方法，但也没有用

# ../myproject/main.py

# Import globfile    
import globfile

# Save myList into globfile
globfile.myList = []

# Import subfile
import subfile

# Do something
subfile.stuff()
print(globfile.myList[0])

在 subfile.py 里面我有这个:

# ../myproject/subfile.py

# Import globfile
import globfile

# Save "hey" into myList
def stuff():
    globfile.myList.append("hey")

但同样，它没有用.我应该如何实施?我知道它不能那样工作，当两个文件并不真正相互了解时(以及子文件不知道主文件)，但我想不出如何做到这一点，而不使用 io 写作或泡菜，这我不想做.

But again, it didn't work. How should I implement this? I understand that it cannot work like that, when the two files don't really know each other (well subfile doesn't know main), but I can't think of how to do it, without using io writing or pickle, which I don't want to do.

推荐答案

问题是你从 main.py 定义了 myList，但是 subfile.py 需要使用它.这里有一个干净的方法来解决这个问题:将所有全局变量移动到一个文件中，我称这个文件为 settings.py.这个文件负责定义全局变量并初始化它们:

The problem is you defined myList from main.py, but subfile.py needs to use it. Here is a clean way to solve this problem: move all globals to a file, I call this file settings.py. This file is responsible for defining globals and initializing them:

# settings.py

def init():
    global myList
    myList = []

接下来，您的 subfile 可以导入全局变量:

Next, your subfile can import globals:

# subfile.py

import settings

def stuff():
    settings.myList.append('hey')

请注意，subfile 不会调用 init()——该任务属于 main.py:

Note that subfile does not call init()— that task belongs to main.py:

# main.py

import settings
import subfile

settings.init()          # Call only once
subfile.stuff()         # Do stuff with global var
print settings.myList[0] # Check the result

通过这种方式，您可以实现目标，同时避免多次初始化全局变量.

This way, you achieve your objective while avoid initializing global variables more than once.

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