Class: SpecialRatio::Ratio

Inherits:
Object
  • Object
show all
Defined in:
lib/special_ratio/ratio.rb

Direct Known Subclasses

GoldenRatio, SilverRatio

Constant Summary collapse

VALID_KEYS = 
[:long, :short, :sum]

Instance Method Summary collapse

Constructor Details

#initialize(params) ⇒ Ratio

Returns a new instance of Ratio.



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# File 'lib/special_ratio/ratio.rb', line 5

def initialize(params)
  params = params.select { |k, v| VALID_KEYS.include?(k) }

  unless params.size == 1
    raise ArgumentError, ':long or :short or :sum is required'
  end

  @key, @value = params.map { |k, v| [k, v] } .flatten
end

Instance Method Details

#long ⇒ Object 



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# File 'lib/special_ratio/ratio.rb', line 15

def long
  case @key
  when :long
    @value
  when :short
    @value * @ratio
  when :sum
    @value * (@ratio / (@ratio + 1))
  end
end

#short ⇒ Object 



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# File 'lib/special_ratio/ratio.rb', line 26

def short
  case @key
  when :long
    @value / @ratio
  when :short
    @value
  when :sum
    @value / (@ratio + 1)
  end
end

#sum ⇒ Object 



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# File 'lib/special_ratio/ratio.rb', line 37

def sum
  case @key
  when :long
    @value * ((@ratio + 1) / @ratio)
  when :short
    @value * (@ratio + 1)
  when :sum
    @value
  end
end