[Python-ideas] Smallest/Largest singletons

Scott Dial scott+python-ideas at scottdial.com
Fri Nov 14 08:25:42 CET 2008

George Sakkis wrote:
> One small side-effect of not being able to compare incompatible types in
> 3.0 is that None cannot be used any more as the smallest element. Yes
> this has always been an implementation artifact and a hack, but it was
> very convenient none the less. Is it maybe the right time to add a
> builtin Smallest (and also Largest) object, i.e. two singletons so that
> `Smallest < x` for every x: x is not Smallest and `Largest > x` for
> every x: x is not Largest ? Although it's not hard to define them in
> pure Python and one could object with "not every n-liner needs to be a
> builtin", the main added value is that these will be endorsed as the
> standard, otherwise we risk mymodule.Smallest clashing with with
> yourmodule.Smallest.

You can more-or-less take all of the replies to the thread about a
blessed "__missing__" object and apply them to "Smallest"/"Largest".
Using special objects to be lazy with your algorithm will never be wise.
Eventually, someone will use them to mean something else entirely. It's
almost always better to avoid using special objects or to roll-your-own
(so that nobody can use it unexpectedly). Furthermore, preloading an
output value with a nonsense value like "Smallest" or "Largest" is just
asking for it to get leaked accidentally (the same problem exists with
preloading None).

-1 Let's not provide features for misguided programming idioms.

Scott Dial
scott at scottdial.com
scodial at cs.indiana.edu

More information about the Python-ideas mailing list