Module: NilComparable

Defined in:
lib/carat/nil-comparable.rb

Overview

# Calling this method for a given class allows instances # of a class to be compared to nil using <=>. # Adapted from code by Paul Brannan (Ruby License) # NOTE: THIS SHOULD BE A CLASS INCLUDING MODULE, I THINK. def nil_comparable(klass=self)

klass.class_eval %{
  if method_defined?( :<=> )
    alias_method :compare_without_nil, :<=>
  else
    def compare_without_nil( other )
      raise TypeError, "Cannot compare \#{self.inspect} to \#{other.inspect}"
    end
  end
  def <=>( other )
    return 1 if other.nil?
    compare_without_nil( other )
  end
}

end

Class Method Summary collapse

Class Method Details

.included(mod) ⇒ Object 



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# File 'lib/carat/nil-comparable.rb', line 49

def self.included( mod )
  mod.class_eval %{
    if method_defined?( :<=> )
      alias_method :compare_without_nil, :<=>
    else
      def compare_without_nil( other )
        raise TypeError, "Cannot compare \#{self.inspect} to \#{other.inspect}"
      end
    end
    def <=>( other )
      return 1 if other.nil?
      compare_without_nil( other )
    end
  }
end