Class: Xchange

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/xchange.rb,
lib/xchange/version.rb

Constant Summary collapse

VERSION = 
"0.1.0"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(amount, currency) ⇒ Xchange

Creates a new Xchange object of value given by amount parameter, with the currency given by the currency parameter

Examples:

Xchange.new(100, "USD") #=> "100.00 USD"
Xchange.new(100, "EUR") #=> "100.00 EUR"


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# File 'lib/xchange.rb', line 81

def initialize (amount, currency)

  #Amount is stored in BigDecimal for better precision in currency operations
  @amount_bigdecimal = BigDecimal.new(amount,0)

  @currency = currency

end

Instance Attribute Details

#amount_bigdecimal ⇒ Object (readonly)

Accessor method



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# File 'lib/xchange.rb', line 74

def amount_bigdecimal
  @amount_bigdecimal
end

#currency ⇒ Object (readonly)

Accessor method



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# File 'lib/xchange.rb', line 74

def currency
  @currency
end

Class Method Details

.conversion_rates(base_currency, rates) ⇒ Object

Class method that configure the currency rates with respect to a base currency

Examples:

Xchange.conversion_rates('EUR',{'USD' => 1.11, 'bitcoin' => 0.00047})


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# File 'lib/xchange.rb', line 94

def self.conversion_rates(base_currency, rates)

  @@base_currency = base_currency

  @@rates = rates

end

Instance Method Details

#*(number) ⇒ Object

Multiplies the amount by a given number



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# File 'lib/xchange.rb', line 188

def *(number)

  #performs the multiplication in BigDecimal
  amount= @amount_bigdecimal * BigDecimal(number,0)

  #returns the result as a new instance
  Xchange.new(amount,@currency)

end

#+(another_currency) ⇒ Object

Performs an addition between the current instance and another one and returns the result as a new Xchange instance



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# File 'lib/xchange.rb', line 165

def +(another_currency)

  #converts the given instance in the actual currency and sums the amounts
  amount = @amount_bigdecimal + another_currency.convert_to(@currency).amount

  #returns the result as a new instance
  Xchange.new(amount,@currency)

end

#-(another_currency) ⇒ Object

Performs a subtraction between the current instance and another one and returns the result as a new Xchange instance



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# File 'lib/xchange.rb', line 177

def -(another_currency)

  #converts the given instance in the actual currency and substracts the amounts
  amount= @amount_bigdecimal - another_currency.convert_to(@currency).amount

  #returns the result as a new instance
  Xchange.new(amount,@currency)

end

#/(number) ⇒ Object

Divides the amount by a given number



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# File 'lib/xchange.rb', line 199

def /(number)

  #performs the division in BigDecimal
  amount= @amount_bigdecimal / BigDecimal(number,0)

  #returns the result as a new instance
  Xchange.new(amount,@currency)

end

#<=>(another_currency) ⇒ Object

<=> implementation allows the comparison between two Xchange instances through the Comparable mixin



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# File 'lib/xchange.rb', line 156

def <=>(another_currency)

  #converts the given instance in the actual currency and compares the amounts
  @amount_bigdecimal <=> another_currency.convert_to(@currency).amount_bigdecimal

end

#amount ⇒ Object

Convenience method for amount, it returns the value in float rounded by two decimals.



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# File 'lib/xchange.rb', line 103

def amount

  @amount_bigdecimal.to_f.round(2)

end

#convert_to(new_currency) ⇒ Object

Converts an instance to another currency

Xchange.new(50, ‘EUR’).convert_to(‘USD’) #=> “55.50 USD”



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# File 'lib/xchange.rb', line 120

def convert_to(new_currency)

  # if the instance is already in the requested currency
  if @currency == new_currency

    #returns itself without conversions
    return self

  # if  the current currency is different from the base currency used for conversions
  # and also the new currency is different from the base one
  elsif @currency != @@base_currency && new_currency != @@base_currency

    # amount is divided by the rate of the current currency in order to convert it to the base currency
    # then is multiplied by the rate of the new currency
    amount = (@amount_bigdecimal/(BigDecimal(@@rates[@currency],0))) * (BigDecimal(@@rates[new_currency],0))

  # current currency is different from the base currency but new currency equals the base currency
  elsif @currency != @@base_currency && new_currency == @@base_currency

    # amount is divided by the rate of the current currency in order to convert it to the base currency
    amount = (@amount_bigdecimal  / @@rates[@currency])

  # current currency must be equal to the base currency and be different from the new currency
  else

    # amount is multiplied for the rate of the new currency
    amount = @amount_bigdecimal * (BigDecimal.new(@@rates[new_currency],0))

  end

  # A new istance is returned with the new currency and the calculated amount
  Xchange.new(amount,new_currency)

end

#inspect ⇒ Object

Convenience method that overrides the output of inspect



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# File 'lib/xchange.rb', line 110

def inspect

  "#{'%.02f' % (@amount_bigdecimal)} #{@currency}"

end