Python 中跨文件共享的静态变量 [英] Static variables in Python that are shared across files

问题描述

我对 Python 很陌生，我找不到一种方法来让静态变量在不同的 Python 文件之间共享......在 Java 中，这样做似乎很简单......这就是我我正在尝试:

I am pretty new to Python and I could't find a way to have static variables that are shared across different python files... In Java, it seems quite straight forward to do so... Here is what I'm trying to do:

data.py

class Shared(object):
    list_vars = []
    var = ""

    @staticmethod
    def print_vars():
        print "list_vars = " + str(Shared.list_vars)
        print "var = " + Shared.var

user1.py

import time
from data import Shared

Shared.list_vars.append("001")
time.sleep(5.0)
Shared.print_vars()

# It prints:
# list_vars = ['001']
# var =

user2.py

import time
from data import Shared

Shared.var = "002"
time.sleep(5.0)
Shared.print_vars()

# It prints:
# list_vars = []
# var = 002

对不起，这可能不是最好的例子，但它抓住了这个想法......我的问题是，如果我想要:

Sorry, this may not be the best example but it catches the idea... my question is, if I want to have:

list_vars = ['001']
var = 002

在运行 user1.py 和 user2.py 后，在其中一个/甚至一些其他 python 文件或类中(我将 user1.py 和 user2.py 视为同一软件包中的两个子程序，它们通常被同时运行)，这样做的Python方式"是什么?

in one of the/even some other python files or classes after running both user1.py and user2.py (I am considering user1.py and user2.py as two sub-programs in the same software package that are normally being run at the same time), what is the "Python way" to do so?

非常感谢！

================================

问题更新:

为了更具体一点，请允许我这样描述问题:

To be a little more specific to the problem, please allow me to describe the problem in this way:

data.py

class Shared(object):
    list_vars = []
    var = ""

    @staticmethod
    def print_vars():
        print "list_vars = " + str(Shared.list_vars)
        print "var = " + Shared.var

    # Can be considered as a separate thread running in the background, waiting for messages
    @staticmethod
    def callback(message):
        if message.event == "add":
            Shared.list_vars.append(message.data)
        elif message.event == "remove" and message.data in Shared.list_vars:
            Shared.list_vars.remove(message.data)

有两个额外的文件，user1.py 和 user2.py，它们的内容可以忽略暂时...

There are two extra files, user1.py and user2.py, their content can be ignored for the moment...

假设 user1.py 和 user2.py 几乎同时运行，说时间 = 0.

So let's say user1.py and user2.py are being run at about the same time, say time = 0.

• 在时间 = 1 时，有消息传入(message.event = "add"和 message.data = "001")，回调 函数在data.py 被触发并且 "001" 被添加到变量 list_vars.

在时间 = 2 时，user1.py 更新变量 vardata.py 到 002".

At time = 2, user1.py updates the variable var in data.py to "002".

在时间 = 3 时，如果 user2.py 想要访问并打印出变量 list_vars 和 var，具有最新值:

At time = 3, if user2.py wants to access and print out the variables list_vars and var, with the latest values:

• list_vars = ["001"]
• var = 002

如何在 Python 中实现这一点?

How can this be achieved in Python?

非常感谢！

推荐答案

问题是(我想)你是分开启动 user1.py 和 user2.py.所以 Shared 类的静态值不会在不同的调用中保留.

The problem is that (I suppose) you are launching separately user1.py and user2.py. So static values of class Shared are not preserved across different invocations.

但这是一种完全正确的数据共享方式:您在一个文件中声明类甚至变量，然后在其他文件中导入.

But that's otherwise a perfectly correct way of sharing data : you declare classes or even variable in one file that is imported in the others.

但是 Python 不是 Java，一切都不需要是一个类.你可以这样做:

But Python is not Java, and everything does not need to be a class. You could do :

• data.py

• data.py

list_vars = []
var = ""

def print_vars():
    print "list_vars = " + str(Shared.list_vars)
    print "var = " + Shared.var

user1.py

user1.py

import time
import data as shared

shared.list_vars.append("001")
time.sleep(5.0)
shared.print_vars()

# It prints:
# list_vars = ['001']
# var =

user2.py

user2.py

import time
import data as shared

shared.var = "002"
time.sleep(5.0)
shared.print_vars()

# It prints:
# list_vars = []
# var = 002

main.py

main.py

import user1
# It prints:
# list_vars = ['001']
# var =
import user2
# It prints:
# list_vars = ['001']
# var = 002

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