Infinity

A full featured Infinity class, supporting signed direction. Inifinty is a multiton based on direction The constant INFINITY is provided as the common case with direction=+1 (positive).

Besides being an class, these four constants are preset: 

  NaN
  Inf
  PosInf
  NegInf

These four constants a built from two other basic constants: 

  UNDEFINED
  INFINITY

In physical memory there are actually only three objects, namely three instances of InfinityClass, one for NaN, PosInf and NegInf, respectively.

Methods
Included Modules
Classes and Modules
Class InfinityClass::Numeric
Constants
UNDEFINED = InfinityClass.new(0)
  Set constant to positive infinity.
INFINITY = InfinityClass.new(1)
NaN = UNDEFINED
Inf = INFINITY
PosInf = +INFINITY
NegInf = -INFINITY
Attributes
[R] direction
Public Class methods
new(direction=1)

[ show source ]

# File lib/more/facets/infinity.rb, line 73
  def initialize(direction=1)
    @direction = (direction <=> 0)
    super()
  end
Public Instance methods
+@()

Noop.

[ show source ]

# File lib/more/facets/infinity.rb, line 90
  def +@
    self
  end
-@()

Change direction of infinity.

[ show source ]

# File lib/more/facets/infinity.rb, line 80
  def -@
    case @direction
    when  0 : self.class.instance(0)
    when  1 : self.class.instance(-1)
    when -1 : self.class.instance(1)
    end
  end
<=>(other)

Comparision where infinity is alway greatest and negative infinityalways least.

[ show source ]

# File lib/more/facets/infinity.rb, line 136
  def <=>(other)
    case other
    when InfinityClass
      @direction <=> other.direction
    else
      @direction
    end
  end
==(other)

Equality. Note that NaN != NaN.

[ show source ]

# File lib/more/facets/infinity.rb, line 120
  def ==(other)
    case other
    when InfinityClass
      if @direction == 0 and other.direction == 0
        false
      else
        super
      end
    else
      false
    end
  end
coerce(other)

Coerce allows other numbers to be compared to infinity.

[ show source ]

# File lib/more/facets/infinity.rb, line 109
  def coerce(other)
    case other
    when InfinityClass
      super
    else
      return -self, other
    end
  end
times() {|end| ...}

Gee, a real infinite loop!

[ show source ]

# File lib/more/facets/infinity.rb, line 102
  def times
    loop do yield end
  end

  # Coerce allows other numbers to be
  # compared to infinity.

  def coerce(other)
    case other
    when InfinityClass
      super
    else
      return -self, other
    end
  end

  # Equality. Note that NaN != NaN.

  def ==(other)
    case other
    when InfinityClass
      if @direction == 0 and other.direction == 0
        false
      else
        super
      end
    else
      false
    end
  end

  # Comparision where infinity is alway greatest
  # and negative infinityalways least.

  def <=>(other)
    case other
    when InfinityClass
      @direction <=> other.direction
    else
      @direction
    end
  end

  #

  def to_s
    case @direction
    when  0  : "NaN"
    when  1  : "PosInf"
    when -1  : "NegInf"
    end
  end

end
to_f()

Convert to the float version of infinity.

[ show source ]

# File lib/more/facets/infinity.rb, line 96
  def to_f
    (1.0/0) * @direction
  end
to_s()

[ show source ]

# File lib/more/facets/infinity.rb, line 147
  def to_s
    case @direction
    when  0  : "NaN"
    when  1  : "PosInf"
    when -1  : "NegInf"
    end
  end