Empact-money

= Money $

This library aids one in handling money and different currencies. Features:

• Provides a Money class which encapsulates all information about an certain amount of money, such as its value and its currency.
• Represents monetary values as integers, in cents. This avoids floating point rounding errors.
• Provides APIs for exchanging money from one currency to another.
• Has the ability to parse a money string into a Money object.
• Provides ActiveRecord "has_money" method.

Resources:

• Website: http://money.rubyforge.org
• RDoc API: http://money.rubyforge.org
• This fork: http://github.com/ShadowBelmolve/money
• Forked from: http://github.com/nofxx/money
• Git repository: http://github.com/FooBarWidget/money/tree/master

== Download

Install stable releases with the following command:

gem install money

The development version (hosted on Github) can be installed with:

gem sources -a http://gems.github.com gem install nofxx-money

== Usage

=== Synopsis

require 'money'

10.00 USD

money = Money.new(1000, "USD") money.cents # => 1000 money.currency # => "USD" money.format # => "$10.00"

Money.new(880088, "EUR").format # => €8,800.88 Money.new(-8000).format(:no_cents => true) # => $-80

Money.new(1000, "USD") == Money.new(1000, "USD") # => true Money.new(1000, "USD") == Money.new( 100, "USD") # => false Money.new(1000, "USD") == Money.new(1000, "EUR") # => false

=== Currency Exchange

Exchanging money is performed through an exchange bank object. The default exchange bank object requires one to manually specify the exchange rate. Here's an example of how it works:

Money.add_rate("CAD", 0.803115) Money.add_rate("USD", 1.24515)

Money.us_dollar(100_00).exchange_to("CAD") # => Money.new(15504, "CAD") Money.ca_dollar(100_00).exchange_to("USD") # => Money.new(6450, "USD")

or

Money.us_dollar(100).as_cad # => Money.new(155, "CAD") Money.ca_dollar(100).as_usd # => Money.new(64, "USD")

Comparison and arithmetic operations work as expected:

Money.new(1000, "USD") <=> Money.new(900, "USD") # => 1; 9.00 USD is smaller Money.new(1000, "EUR") + Money.new(10, "EUR") == Money.new(1010, "EUR")

Money.add_rate("EUR", 0.5) Money.new(1000, "EUR") + Money.new(1000, "USD") == Money.new(1500, "EUR")

Fetch the exchange rates published by the European Bank

Money.default_bank.fetch_rates # Fetch the rates Money.default_bank.auto_fetch 3600 # Fetch the rates every hour Money.default_bank.stop_fetch # Stop auto-fetch

There is nothing stopping you from creating bank objects which scrapes www.xe.com for the current rates or just returns rand(2):

Money.default_bank = ExchangeBankWhichScrapesXeDotCom.new

=== Ruby on Rails

Use the +has_money+ method to embed the money object in your models. The following example requires a +price_cents+ and a +price_currency+ fields on the database.

config/enviroment.rb

require.gem 'nofxx-money', :lib => 'money'

app/models/product.rb

class Product < ActiveRecord::Base belongs_to :product has_money :price

validates_numericality_of :price_cents, :greater_than => 0

end

migration:

create_table :products do |t| t.integer :price_cents t.string :price_currency end

=== Default Currency

By default Money defaults to USD as its currency. This can be overwritten using:

Money.default_currency = "CAD"

If you use Rails, then environment.rb is a very good place to put this.

== TODO

• Better validation (fix composed_of allow_nil)
• Interest (almost there..)
• Remote rate fetching