Keeping a database connection with a Singleton?

[Jason]

On Sep 19, 7:26 am, "exhuma.twn" <exh... at gmail.com> wrote:
> I remember reading about the Singleton pattern in python and how it's
> an unpythonic pattern and all. At the time I did not need the
> Singleton anyways, so I just glanced over the document.
>
> But, setting this aside: I have an application where I have a
> connection to a database. At some point in the application I open up a
> new window. The new windows resides in a different module. So I have a
> directory structure like this:
>
> - mainapp.py
> - newwindow.py
>
> So I import "newwindow" in "mainapp"  so I can instantiate and display
> it. Meanwhile, the main-app has an open connection to the database.
> What's the cleanest way to hand this connection to the new window? I
> can see several possibilities:
>
> 1) Simply pass the connection as paramtere to the constructor of new-
> window.
> 2) Use the "Singleton" deisign pattern to keep a reference to the
> connection
> 3) Open up a completely new connection to the database in the new
> window.
>
> Now, option 1) is clearly the easiest to implement, however, I somehow
> tend to use option 2 (the singleton) as it's more flexible. Option 3
> looks ugly to me.
>
> This is a stuation I run into many times. And I am always faced with
> the same choice. And I never know which one to chose. And now that I
> am getting more and more comfortable with the basics of python, I
> would like to know if I am missing something more "pythonic".
>
> So, what would you recommend?

You don't need a way to make every instance the same.  You need a way
where every instance shares the same state.  Aka, the Borg pattern,
courtesy of Alex Martelli.  It's in the Python Cookbook at "http://
aspn.activestate.com/ASPN/Cookbook/Python/Recipe/66531".  Good luck!

  --Jason