How to implement a singleton model

Question

I have a site in rails and want to have site-wide settings. One part of my app can notify the admin by SMS if a specific event happens. This is an example of a feature that

Answer 1

Odds are good you don't need a singleton. It's unfortunate that one of the worst design habits to come out of the patterns craze is also one of the most commonly adopted. I blame the unfortunate appearance of simplicity, but I digress. If they had called it the "Static Global" pattern I'm sure people would have been more sheepish about using it.

I suggest using a wrapper class with a private static instance of the class you want to use for the singleton. You won't introduce a tight couple throughout your code like you will with the singleton.

Some people call this a monostate pattern. I tend to think of it as just another twist on the strategy/agent concept since you can allow for more flexibility by implementing different interfaces to expose/hide functionality.