conversions.rb in conversions-1.4.3

- old
+ new
@@ -1,46 +1,59 @@
-module UnitConversions
-  UNITS = ['kg', 'g', 't', 'mm2', 'm2']
-  CONVERT_TO_PATTERN = /(#{UNITS.join('|')})_to_(#{UNITS.join('|')})/
-  CONVERSIONS = {
-    'kg' => {
-      't' => lambda() {|kg| kg / 1000.0 },
-      'g' => lambda() {|kg| kg * 1000 },
-    },
-    'g' => {
-      'kg' => lambda() {|g| g / 1000.0},
-      't' => lambda() {|g| g / (1000.0 * 1000) },
-    },
-    't' => {
-      'kg' => lambda() {|t| t * 1000},
-      'g' => lambda() {|t| t * (1000 * 1000)},
-    },
-    'm2' => {
-      'mm2' => lambda() {|m2| m2 * (1000 * 1000.0)},
-    },
-    'mm2' => {
-      'm2' => lambda() {|mm2| mm2 / (1000 * 1000.0)},
-    },
-  }
+# Conversions makes it easy to convert between units.
+module Conversions
+  mattr_accessor :conversions
+
+  # Clear all previously registered conversions
+  def self.clear
+    self.conversions = {}
+  end
+  clear
   
-  
-  def method_missing_with_unit_conversions(m, *args)
-    if args.length == 0
-      m.to_s =~ CONVERT_TO_PATTERN    
-      return CONVERSIONS[$1][$2].call(self) if CONVERSIONS[$1] && CONVERSIONS[$1][$2]
+  # Load all the default conversions shipped with the code
+  def self.load_defaults
+    load File.expand_path('../conversions/defaults.rb', __FILE__)
+  end
+
+  # Register a new conversion. This automatically also registers the inverse conversion.
+  #
+  # * _from_: The unit to convert from (ie. :miles, :stones, or :pints)
+  # * _to_: The unit to convert to
+  # * _rate_: The conversion rate from _from_ to _to_. (_from_ * _rate_ = _to_)
+  def self.register(from, to, rate)
+    conversions[from] ||= {}
+    conversions[from][to] = rate
+    conversions[to] ||= {}
+    conversions[to][from] = 1.0 / rate
+    Conversions.define_shortcut(from)
+    Conversions.define_shortcut(to)
+  end
+
+  def self.define_shortcut(unit)
+    Numeric.class_eval do
+      define_method unit do
+        Conversions::Unit.new(self, unit)
+      end unless respond_to? unit
     end
-    method_missing_without_unit_conversions(m, args)
   end
-  
-end
 
-class Fixnum
-  include UnitConversions
-  alias :method_missing_without_unit_conversions :method_missing
-  alias :method_missing :method_missing_with_unit_conversions
+  module Ext
+    # Convert from one unit to another.
+    #
+    # * _from_: The unit to convert from (ie. :miles, :stones, or :pints)
+    # * _to_: The unit to convert to
+    # * _options_:
+    #   * :scale: The number of digits you want after the dot.
+    def convert(from, to, options={})
+      Conversions::Unit.new(self, from).to(to, options)
+    end
+  end
 end
 
-class Float
-  include UnitConversions
-  alias :method_missing_without_unit_conversions :method_missing
-  alias :method_missing :method_missing_with_unit_conversions
+require 'conversions/unit'
+
+Conversions.load_defaults
+Numeric.send(:include, Conversions::Ext)
+
+if defined?(ActiveRecord)
+  require 'conversions/active_record_accessors'
+  ActiveRecord::Base.send(:extend, Conversions::ActiveRecordAccessors)
 end
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