Tag Archives: singleton

Example for singleton decorator pattern in python

I know there is not very common in Python to use the singleton pattern, but I found a nice implementation of this pattern in Python 3 Patterns, Recipes and Idioms book. Starting with that example I implemented an equivalent of the well known PHP getConnection example.

You have the code below:

This is the class that implements the Singleton pattern.

Now, we create a class and we decorate it with the Singleton class. Let’s import also MySQLdb module *.

Let’s test this:

You will see something like:

As you can see there is only one object.

For fun, let’s remove the line “@Singleton” and re-run the example. This time you will see different objects:

You can find the fully example here.

* If you don’t know how to install MySQLdb, you can check the previous post.

Singleton Pattern

This pattern is probably one of the most simple and used pattern.

As php manual says: The Singleton pattern applies to situations in which there needs to be a single instance of a class. The most common example of this is a database connection. Implementing this pattern allows a programmer to make this single instance easily accessible by many other objects.

There are tons of information about this pattern over the Internet so I let you google for it.

You can find a singleton implementation in Simple MVC framework example.