修改从…导入的模块中的变量*

Consider the following code:

考虑下面的代码:

#main.py
From toolsmodule import *
database = "foo"

#toolsmodule
database = "mydatabase"

As it seems, this creates one variable in each module with different content. How can I modify the variable inside toolsmodule from main? The following does not work:

看起来，这在每个模块中创建了一个具有不同内容的变量。如何从main修改toolsmodule内部的变量?以下不可行:

toolsmodule.database = "foo"

3 个解决方案

#1

Sounds like yet another of the multitude of good reasons not to use from toolsmodule import *.

这听起来像是众多不使用工具结构导入的好理由之一*。

If you just do import toolsmodule, then you can do toolsmodule.database = 'foo', and everything is wonderful.

如果您只做导入工具烟雾，那么您可以做工具烟雾。数据库= 'foo'，一切都很棒。

#2

Pythons variable names are just labels on variables. When you import * all those labels are local and when you then set the database, you just replace the local variable, not the one in toolsmodule. Hence, do this:

python变量名只是变量的标签。当您导入*时，所有的标签都是本地的，当您设置数据库时，您只需替换本地变量，而不是toolsmodule中的那个。因此,这样做:

toolsmodule.py:

database = "original"

def printdatabase():
   print "Database is", database

And then run:

然后运行:

import toolsmodule
toolsmodule.database = "newdatabase"
toolsmodule.printdatabase()

The output is

输出是

Database is newdatabase

Note that if you then from ANOTHER module ALSO did an import * the change is not reflected.

注意，如果您从另一个模块也做了导入*更改没有反映出来。

In short: NEVER use from x import *. I don't know why all newbies persist in doing this despite all documentation I know of says that it's a bad idea.

简而言之:永远不要从x导入*。我不知道为什么所有的新手都坚持这么做，尽管我知道所有的文件都说这是个坏主意。

#3

Why don't you do it like that:

你为什么不这样做呢:

import toolsmodule
toolsmodule.database = "foo"
from toolsmodule import *  #bad idea, but let's say you have to..
print database #outputs foo

#1