From: Thomas Hafner <thomas@...>
Date: 2009-04-25T07:10:14+09:00
Subject: Re: hygienic startup file

Robert Klemme <shortcutter@googlemail.com> wrote/schrieb <9e3fd2c80904240015h11f3376l424a24457691b0c0@mail.gmail.com>:

> The question is: why do you need constants if you want to hide them?

First I defined constants rather than variables simply because each of
them actually is constant rather than variable: the value never
changes after assignment. In C++ I would add a const qualifier to the
local variables, e.g. to prevent from unintentionally overriding it.
In Haskell ther's no need for a const keyword, because all definitions
are immutable per se, which is regarded a feature in this purely
functional programming language.

But in Ruby there are no local constants analogical to local
variables, so when I simply define constants I unintentionally export
them, too. (Freeze is no option, because it freezes the object hold by
the variable, not the variable itself.)

Every alternative has its own tradeoff:
1. If I define simple constants, I pollute the namespace of the
loading code.
2. If I define constants within class << Object.new, the code is
somehow ugly.
3. If I define local variables, I don't benefit from the fact that
they are actually constant.

So currently alternative #3 is best for me, but if somebody shows me a
way to make #2 less ugly (get away from class << Object.new), that
would probably my favorite.

Regards
  Thomas