gistfile1.rb

RATIONALE =<<_END
The case for a maybe:
We all know true and false, right? Larry Wall once said that truth should be
considered evident; therefore anything in Perl is either true or false, along with
anything else it may be. Truth is just an aspect.

And we use it easily, with the if/else construct:

if something
  do_something
else
  do_something_else
end

How about the cases where we don't know? Let's say you're a meteorologist, and somone asks
if it will rain tomorrow. Let's say you don't know, it's a 50/50 chance of each. Would you
accept being forced in to answering yes or no?

if it_will_rain?
  bring_an_umbrella
else
  wear_sunglasses
else
  bring_an_umbrella
  wear_sunglasses
end

Makes sense, doesn't it?
Let's give it a try
_END

require 'singleton'
class MaybeClass
  include Singleton
  def to_s
    "maybe"
  end
end
class Object
  def maybe
    MaybeClass.instance
  end
end

puts maybe

OMG_AN_OPERATOR=<<_END
But wait, if/else is a language construct, isn't it? What would a Smalltalker do in this situation?

In Smalltalk, there is no if/else statement. Instead you use methods on true and false, like this:
it_will_rain?.if_true {
  bring_an_umbrella
}
Let's try
_END

class TrueClass
  def if_true
    yield
  end
  def if_false;end
end

class FalseClass
  def if_true;end
  def if_false
    yield
  end
end

false.if_true {
  puts "No way"
}
true.if_true {
  puts "Why, of course"
}

MAKES_SENSE=<<_END
See where I'm going? 
_END

class FalseClass
  def yes
    self
  end

  def no
    yield
    self
  end

  def maybe
    self
  end
end

class TrueClass
  def yes
    yield
    self
  end

  def no
    self
  end

  def maybe
    self
  end
end

class MaybeClass
  def yes
    self
  end

  def no
    self
  end

  def maybe
    yield
    self
  end
end

def will_it_rain?
  maybe
end

will_it_rain?.yes {
  puts "Bring an umbrella"
}.no {
  puts "Wear sunglasses"
}.maybe {
  puts "Bring an umbrella and wear sunglasses"
}