Module: Currency::Exchange::Rate::Source

Defined in:

lib/currency/exchange/rate/source.rb

Overview

The Currency::Exchange::Rate::Source package is responsible for providing rates between currencies at a given time.

It is not responsible for purchasing or selling actual money. See Currency::Exchange.

Currency::Exchange::Rate::Source::Provider subclasses are true rate data providers. See the #load_rates method. They provide groups of rates at a given time.

Other Currency::Exchange::Rate::Source::Base subclasses are chained to provide additional rate source behavior, such as caching and derived rates. They provide individual rates between currencies at a given time. See the #rate method. An application will interface directly to a Currency::Exchange::Rate::Source::Base. A rate aggregator like Currency::Exchange::Rate::Historical::Writer will interface directly to a Currency::Exchange::Rate::Source::Provider.

IMPORTANT

Rates sources should never install themselves as a Currency::Exchange::Rate::Source.current or Currency::Exchange::Rate::Source.default. The application itself is responsible setting up the default rate source. The old auto-installation behavior of rate sources, like Currency::Exchange::Xe, is no longer supported.

Initialization of Rate Sources

A typical application will use the following rate source chain:

• Currency::Exchange::Rate::Source::TimedCache

• Currency::Exchange::Rate::Deriver

• a Currency::Exchange::Rate::Source::Provider subclass, like Currency::Exchange::Rate::Source::Xe.

Somewhere at initialization of application:

require 'currency'
require 'currency/exchange/rate/deriver'
require 'currency/exchange/rate/source/xe'
require 'currency/exchange/rate/source/timed_cache'

provider = Currency::Exchange::Rate::Source::Xe.new
deriver  = Currency::Exchange::Rate::Deriver.new(:source => provider)
cache    = Currency::Exchange::Rate::Source::TimedCache.new(:source => deriver)
Currency::Exchange::Rate::Source.default = cache

Defined Under Namespace

Classes: Base, Failover, FederalReserve, Historical, NewYorkFed, Provider, Test, TheFinancials, TimedCache, Xe

Constant Summary

@@default =

nil

@@current =

nil

Class Method Summary

• .current ⇒ Object

  Returns the current Currency::Exchange object used during explicit and implicit Money conversions.

• .current=(x) ⇒ Object

  Sets the current Currency::Exchange object used during explicit and implicit Money conversions.

• .default ⇒ Object

  Returns the default Currency::Exchange::Rate::Source::Base object.

• .default=(x) ⇒ Object

  Sets the default Currency::Exchange object.

Class Method Details

.current ⇒ Object

Returns the current Currency::Exchange object used during explicit and implicit Money conversions.

If #current= has not been called and #default= has not been called, then UndefinedExchange is raised.

# File 'lib/currency/exchange/rate/source.rb', line 78

def self.current
  @@current || self.default || (raise ::Currency::Exception::UndefinedExchange, "Currency::Exchange.current not defined")
end

.current=(x) ⇒ Object

Sets the current Currency::Exchange object used during explicit and implicit Money conversions.

# File 'lib/currency/exchange/rate/source.rb', line 84

def self.current=(x)
  @@current = x
end

.default ⇒ Object

Returns the default Currency::Exchange::Rate::Source::Base object.

If one is not specfied an instance of Currency::Exchange::Rate::Source::Base is created. Currency::Exchange::Rate::Source::Base cannot service any conversion rate requests.

# File 'lib/currency/exchange/rate/source.rb', line 64

def self.default 
  @@default ||= Base.new
end

.default=(x) ⇒ Object

Sets the default Currency::Exchange object.

# File 'lib/currency/exchange/rate/source.rb', line 69

def self.default=(x)
  @@default = x
end