使数据库连接可跨许多python模块使用的正确方法 [英] the proper method for making a DB connection available across many python modules

问题描述

我想在多个python模块中使一个数据库对象可用.

I want to make a single database object available across many python modules.

对于与相关的示例，我创建globl.py:

For a related example, I create globl.py:

DOCS_ROOT="c:\docs" ## as an example
SOLR_BASE="http://localhost:8636/solr/"

任何其他需要它的模块都可以做

Any other module which needs it can do a

from globl import DOCS_ROOT

现在除了这个示例之外，我想对数据库连接对象做相同的事情，在许多模块中共享它们.

Now this example aside, I want to do the same thing with database connection objects, share them across many modules.

import MySQLdb
conn = MySQLdb.connect (host="localhost"...)
cursor = conn.cursor()

我在翻译器上尝试过

from globl import cursor

，它似乎有效.但是我怀疑这会每次导入一个模块都会导致执行相同的模块.那么这是正确的方法吗?

and it seems to work. But I suspect that this will cause the same module to be executed each time one imports from it. So is this the proper way?

推荐答案

您猜错了.该代码将仅执行一次-后续导入仅通过sys.modules引用该模块，而无需重新运行它.

You suspect wrongly. The code will only be executed once - subsequent imports just refer to the module via sys.modules, and don't re-run it.

(请注意，只要您始终使用相同的路径来导入模块，就是这种情况-如果您在一个位置执行from globl import cursor，而在另一个位置执行from my.fullyqualified.project.global import cursor，则可能会发现代码重新执行.)

(Note that this is the case as long as you always use the same path to import the module - if you do from globl import cursor in one place, and from my.fullyqualified.project.global import cursor in another, you probably will find the code is re-executed.)

编辑以添加，这是处理全局对象的一种非常好的方法.

Edit to add as S.Lott says in the comment, this is a perfectly good way to handle a global object.

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