Add ISO4217 namespace for Currency class.

From now use "ISO4217::Currency" instead of "Currency".

Note that this is very desirable for Rails projects.
If you have model called "Currency" using this gem witin that Rails
project is complete mess.
Currently we are working on this kind of project.

README.markdown

@@ -16,15 +16,15 @@ Basic Usage
 
 There are two ways to get a currency object. The first is to simply make it.
 
-    Currency.new('USD', :name => 'Dollars', :symbol => '$', :exchange_rate => 1)
+    ISO4217::Currency.new('USD', :name => 'Dollars', :symbol => '$', :exchange_rate => 1)
 
 Or you can lookup a currency by its ISO 4217 code using the *from_code* method.
 
-    Currency.from_code('USD')
+    ISO4217::Currency.from_code('USD')
 
 Once you have a Currency instance you can get basic information about it.
 
-    currency = Currency.from_code('USD')
+    currency = ISO4217::Currency.from_code('USD')
     currency.code #=> "USD"
     currency.name #=> "Dollars"
     currency.symbol #=> "$"
@@ -36,12 +36,12 @@ Adding Currencies
 
 Currencies keeps an internal list of currencies for use in the ExchangeBank and to be looked up with the *from_code* method. By default this list contains all the currencies in the ISO 4217 standard. A custom currency can be added using the *add* class method.
 
-    shiny_button = Currency.new('SBTTN', :name => 'Buttons', :symbol => '☼', :exchange_rate => 1000)
-    Currency.add(shiny_button)
+    shiny_button = ISO4217::Currency.new('SBTTN', :name => 'Buttons', :symbol => '☼', :exchange_rate => 1000)
+    ISO4217::Currency.add(shiny_button)
 
 To do a massive addition of currencies you can load a yaml file using the *load_file* class method.
 
-    Currency.load_file('custom_currency.yaml')
+    ISO4217::Currency.load_file('custom_currency.yaml')
 
 And the yaml file should look like ...
 
@@ -54,19 +54,19 @@ Defaults
 
 You can set the base currency by using the *base_currency* class method. This defaults to 'USD'.
 
-    Currency.base_currency => 'GBP'
+    ISO4217::Currency.base_currency => 'GBP'
 
 The exchange rate is either set manually or if nil looked up on Yahoo Finance and cached. If you want to disable looking up the currency set the *import_exchange_rates* class method to false.
 
-    Currency.import_exchange_rates = false
+    ISO4217::Currency.import_exchange_rates = false
 
 
 Money Gem
 ---------
 
 To use with the money gem you just set the default bank to the currencies bank.
 
-    Money.default_bank = Currency::ExchangeBank.new
+    Money.default_bank = ISO4217::Currency::ExchangeBank.new
 
 The Currencies ExchangeBank works the same as the one in the money gem except that if an exchange rate isn't set by default it uses what is set in the currencies gem.
 

lib/currencies/currency.rb

@@ -1,4 +1,7 @@
-class Currency
+module ISO4217
+end
+
+class ISO4217::Currency
   class << self
     attr_accessor :currencies
     attr_accessor :base_currency
@@ -12,7 +15,7 @@ def initialize(iso_code,opts={})
     @code = iso_code.to_s.upcase
     @name = opts['name']
     @symbol = opts['symbol']
-    @exchange_currency = opts['exchange_currency'] || Currency.base_currency
+    @exchange_currency = opts['exchange_currency'] || self.class.base_currency
     @exchange_rate = opts['exchange_rate'].to_f if opts['exchange_rate']
   end
 
@@ -21,14 +24,14 @@ def [](value)
   end
 
   def exchange_rate
-    @exchange_rate = nil unless @exchange_currency == Currency.base_currency
+    @exchange_rate = nil unless @exchange_currency == self.class.base_currency
     @exchange_rate ||= load_exchange_rate
   end
 
   def load_exchange_rate
-    @exchange_currency = Currency.base_currency
+    @exchange_currency = self.class.base_currency
     return 1.0 if @code == @exchange_currency
-    if Currency.import_exchange_rates
+    if self.class.import_exchange_rates
       http = Net::HTTP.new('download.finance.yahoo.com', 80)
       response = http.get("/d/quotes.csv?e=.csv&f=sl1d1t1&s=#{@code}#{@exchange_currency}=X")
       rate = response.body.split(',')[1]
@@ -49,7 +52,7 @@ def self.from_code(code)
   end
 
   def self.major_currencies_selection(currencies)
-    currencies.select { |code, currency| Currency.major_codes.include?(code) }.first
+    currencies.select { |code, currency| self.major_codes.include?(code) }.first
   end
 
   def self.best_from_currencies(currencies)

lib/currencies/exchange_bank.rb

@@ -1,6 +1,6 @@
 require 'thread'
 
-class Currency
+class ISO4217::Currency
   class ExchangeBank
     def self.instance
       @@singleton
@@ -32,8 +32,8 @@ def exchange(cents, from_currency, to_currency)
       if rate
         (cents * rate).floor
       else
-        from_currency = Currency.from_code(from_currency)
-        to_currency = Currency.from_code(to_currency)
+        from_currency = ISO4217::Currency.from_code(from_currency)
+        to_currency = ISO4217::Currency.from_code(to_currency)
 
         if from_currency && to_currency && from_currency.exchange_rate && to_currency.exchange_rate && (from_currency.exchange_currency == to_currency.exchange_currency)
           ((cents * from_currency.exchange_rate) / to_currency.exchange_rate).floor
@@ -45,4 +45,4 @@ def exchange(cents, from_currency, to_currency)
 
     @@singleton = ExchangeBank.new
   end
-end
+end