Singleton?

[Jason Orendorff]

James T. Dennis wrote:
> Jason Orendorff wrote:
> > There are many approaches.  My favorite, when it's feasible, is:
> >
> >   class _X:
> >       """ NOTE: Do not instantiate this class!  Use x instead. """
> >       pass
> >
> >   x = _X()  # singleton instance
> 
>  This is similar to an option I considered: [...]

Perhaps it *looks* similar, but I assure you it's quite different
in spirit.  The point of my approach above is:

 - Anyone can write it.
 - Anyone can read it.
 - It uses no "tricks" or advanced language features.
 - It's the quickest, simplest thing.

My favorite Singleton in the Python standard library
is class random.Random.  Consult the source (lines 633+)
for all the clever details.

(To find the source file, try
    python -e "import random; print random.__file__"
 but the source is in the .py file, not the .pyc file.)

## Jason Orendorff    http://www.jorendorff.com/