From: John Joyce <dangerwillrobinsondanger@...>
Date: 2007-10-10T02:29:21+09:00
Subject: Re: Make a class evaluate to false in boolean expressions


On Oct 9, 2007, at 10:53 AM, Matt Margolis wrote:

> I want to have a class that always evaluates to false in boolean  
> expressions.  Is there a way to extend Ruby so that it evaluates an  
> object of a class to false like false and nil?
>
> Example
>
> class AlwaysFalse
> end
>
> should_be_false = AlwaysFalse.new
>
> if should_be_false
>  #I don't want this to ever run
> else
>  #will always run
> end
This is your design problem.
You can't change the language to do what it doesn't do.
What you want is probably not a class if it always returns false.
You want a constant value.
You can create a class with an instance or class variable that  
happens to be a constant. (no setter, only a getter)
so you might do

The problem is your if will go to else if the should_be_false is  
false. not clear logic in the code.
Just do it the Ruby way, create a method or function:
  my_class.false?
or
  false?( my_arg )

This way the logic is more obvious and clear like natural language.