[Tutor] Cross-Module Interaction

[Corey Richardson]

On 02/26/2011 12:11 AM, Steven D'Aprano wrote:
> [steve at sylar ~]$ python
> Python 2.5 (r25:51908, Nov  6 2007, 16:54:01)
> [GCC 4.1.2 20070925 (Red Hat 4.1.2-27)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
>  >>> import lib
>  >>> import a
>  >>> lib.g
> []
>  >>> a.do_stuff()
>  >>> lib.g
> [42]
> 
> 
> Of course, when your application exists (or in this case, the 
> interactive session), the changes to lib.g will be lost because they 
> only exist in memory. If you want data to persist across application 
> runs, you need to arrange for the application to save the data to disk, 
> and then read it again when it starts up.

Aha, that explains why I didn't get any results. Each file got its own
interpreter instance.

> 
> Python has many tools for working with persistent data: Windows-style 
> ini files (module config parser), XML, JSON, Mac-style plists, YAML 
> (third-party module only), and pickles, to name only a few.

In any case everything would be called in one interpreter, which I
didn't know worked because I didn't test it like you showed it, but to
be safe I definitely need to persist that data every once in a while.

I'm slightly concerned about performance when it comes to
reading/writing to disk a lot when doing things like that, since if this
thing ever needs to scale I want it to be able to do that.

Thank you, Steven
-- 
Corey Richardson