Here is a weird abuse of default variable values to support shorthand variable names. It’s valid Ruby.

[ruby] def area(r=radius) { Math::pi * r * r } [/ruby]

Simple example, but you get the point. It lets you tell the external world what a parameter is all about, but keeps the implementation shorthand. Obviously it’s just a simple example here; parameter names can be much more verbose than just this example and functions can be longer, so you don’t want to keep repeating a long name. For example:

[ruby] def damage_level(force_exterted_by_car=force) { force = 0 if force < 0 acceleration = mass/force … } [/ruby]

Now you might say “just declare it in the first line”, but I prefer small code and there could be several such lines.

You might say “mention it in a comment”, but I prefer self-documenting code. Comments go out of date and clutter up code. (Strictly speaking, the long name here is a comment, but it’s more likely to be maintained.)

[Update: I don’t often mention Pi, but when I do, it’s on March 14: Pi Day. Thanks to the reader who pointed it out!]