Class for aiding in exchanging money between different currencies. By default, the Money class uses an object of this class (accessible through +Money#bank+) for performing currency exchanges.
By default, +Money::Bank::VariableExchange+ has no knowledge about conversion rates. One must manually specify them with add_rate, after which one can perform exchanges with #exchange_with.
@example
bank = Money::Bank::VariableExchange.new bank.add_rate("USD", "CAD", 1.24515) bank.add_rate("CAD", "USD", 0.803115) c1 = 100_00.to_money("USD") c2 = 100_00.to_money("CAD") # Exchange 100 USD to CAD: bank.exchange_with(c1, "CAD") #=> #<Money @fractional=1245150> # Exchange 100 CAD to USD: bank.exchange_with(c2, "USD") #=> #<Money @fractional=803115>
Available formats for importing/exporting rates.
Registers a conversion rate and returns it (uses #set_rate).
@param [Currency, String, Symbol] from Currency to exchange from. @param [Currency, String, Symbol] to Currency to exchange to. @param [Numeric] rate Rate to use when exchanging currencies.
@return [Numeric]
@example
bank = Money::Bank::VariableExchange.new bank.add_rate("USD", "CAD", 1.24515) bank.add_rate("CAD", "USD", 0.803115)
# File lib/money/bank/variable_exchange.rb, line 133 def add_rate(from, to, rate) set_rate(from, to, rate) end
# File lib/money/bank/variable_exchange.rb, line 103 def calculate_fractional(from, to_currency) BigDecimal.new(from.fractional.to_s) / ( BigDecimal.new(from.currency.subunit_to_unit.to_s) / BigDecimal.new(to_currency.subunit_to_unit.to_s) ) end
# File lib/money/bank/variable_exchange.rb, line 110 def exchange(fractional, rate, &block) ex = (fractional * BigDecimal.new(rate.to_s)).to_f if block_given? yield ex elsif @rounding_method @rounding_method.call(ex) else ex.to_s.to_i end end
Exchanges the given Money object to a new Money object in to_currency.
@param [Money] from
The +Money+ object to exchange.
@param [Currency, String, Symbol] to_currency
The currency to exchange to.
@yield [n] Optional block to use when rounding after exchanging one
currency for another.
@yieldparam [Float] n The resulting float after exchanging one currency
for another.
@yieldreturn [Integer]
@return [Money]
@raise +Money::Bank::UnknownRate+ if the conversion rate is unknown.
@example
bank = Money::Bank::VariableExchange.new bank.add_rate("USD", "CAD", 1.24515) bank.add_rate("CAD", "USD", 0.803115) c1 = 100_00.to_money("USD") c2 = 100_00.to_money("CAD") # Exchange 100 USD to CAD: bank.exchange_with(c1, "CAD") #=> #<Money @fractional=1245150> # Exchange 100 CAD to USD: bank.exchange_with(c2, "USD") #=> #<Money @fractional=803115>
# File lib/money/bank/variable_exchange.rb, line 87 def exchange_with(from, to_currency, &block) to_currency = Currency.wrap(to_currency) if from.currency == to_currency from else if rate = get_rate(from.currency, to_currency) fractional = calculate_fractional(from, to_currency) Money.new( exchange(fractional, rate, &block), to_currency ) else raise UnknownRate, "No conversion rate known for '#{from.currency.iso_code}' -> '#{to_currency}'" end end end
Return the known rates as a string in the format specified. If file is given will also write the string out to the file specified. Available formats are :json, :ruby and :yaml.
@param [Symbol] format Request format for the resulting string. @param [String] file Optional file location to write the rates to. @param [Hash] opts Options hash to set special parameters @option opts [Boolean] :without_mutex disables the usage of a mutex
@return [String]
@raise +Money::Bank::UnknownRateFormat+ if format is unknown.
@example
bank = Money::Bank::VariableExchange.new bank.set_rate("USD", "CAD", 1.24515) bank.set_rate("CAD", "USD", 0.803115) s = bank.export_rates(:json) s #=> "{\"USD_TO_CAD\":1.24515,\"CAD_TO_USD\":0.803115}"
# File lib/money/bank/variable_exchange.rb, line 207 def export_rates(format, file = nil, opts = {}) raise Money::Bank::UnknownRateFormat unless RATE_FORMATS.include? format s = "" fn = -> { s = case format when :json JSON.dump(@rates) when :ruby Marshal.dump(@rates) when :yaml YAML.dump(@rates) end unless file.nil? File.open(file, "w") {|f| f.write(s) } end } if opts[:without_mutex] fn.call else @mutex.synchronize { fn.call } end s end
Retrieve the rate for the given currencies. Uses Mutex to synchronize data access.
@param [Currency, String, Symbol] from Currency to exchange from. @param [Currency, String, Symbol] to Currency to exchange to. @param [Hash] opts Options hash to set special parameters @option opts [Boolean] :without_mutex disables the usage of a mutex
@return [Numeric]
@example
bank = Money::Bank::VariableExchange.new bank.set_rate("USD", "CAD", 1.24515) bank.set_rate("CAD", "USD", 0.803115) bank.get_rate("USD", "CAD") #=> 1.24515 bank.get_rate("CAD", "USD") #=> 0.803115
# File lib/money/bank/variable_exchange.rb, line 178 def get_rate(from, to, opts = {}) fn = -> { @rates[rate_key_for(from, to)] } if opts[:without_mutex] fn.call else @mutex.synchronize { fn.call } end end
Loads rates provided in s given the specified format. Available formats are :json, :ruby and :yaml.
@param [Symbol] format The format of s. @param [String] s The rates string. @param [Hash] opts Options hash to set special parameters @option opts [Boolean] :without_mutex disables the usage of a mutex
@return [self]
@raise +Money::Bank::UnknownRateFormat+ if format is unknown.
@example
s = "{\"USD_TO_CAD\":1.24515,\"CAD_TO_USD\":0.803115}" bank = Money::Bank::VariableExchange.new bank.import_rates(:json, s) bank.get_rate("USD", "CAD") #=> 1.24515 bank.get_rate("CAD", "USD") #=> 0.803115
# File lib/money/bank/variable_exchange.rb, line 253 def import_rates(format, s, opts = {}) raise Money::Bank::UnknownRateFormat unless RATE_FORMATS.include? format fn = -> { @rates = case format when :json JSON.load(s) when :ruby Marshal.load(s) when :yaml YAML.load(s) end } if opts[:without_mutex] fn.call else @mutex.synchronize { fn.call } end self end
# File lib/money/bank/variable_exchange.rb, line 47 def marshal_dump [@rates, @rounding_method] end
# File lib/money/bank/variable_exchange.rb, line 51 def marshal_load(arr) @rates, @rounding_method = arr @mutex = Mutex.new end
Set the rate for the given currencies. Uses Mutex to synchronize data access.
@param [Currency, String, Symbol] from Currency to exchange from. @param [Currency, String, Symbol] to Currency to exchange to. @param [Numeric] rate Rate to use when exchanging currencies. @param [Hash] opts Options hash to set special parameters @option opts [Boolean] :without_mutex disables the usage of a mutex
@return [Numeric]
@example
bank = Money::Bank::VariableExchange.new bank.set_rate("USD", "CAD", 1.24515) bank.set_rate("CAD", "USD", 0.803115)
# File lib/money/bank/variable_exchange.rb, line 152 def set_rate(from, to, rate, opts = {}) fn = -> { @rates[rate_key_for(from, to)] = rate } if opts[:without_mutex] fn.call else @mutex.synchronize { fn.call } end end
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