unit.rb in ruby-measurement-1.1.0

- old
+ new

@@ -2,32 +2,40 @@
 
 class Measurement
   class Unit
     attr_reader :name, :aliases, :conversions
     
-    def initialize(name, &block)
+    @definitions = {}
+    
+    def initialize(name)
       @name = name.to_s
       @aliases = Set.new
       @conversions = {}
-      
-      self.alias(name)
-      block.call(self) if block_given?
+      add_alias(name)
     end
     
-    def alias(*args)
-      args.each { |arg| @aliases << arg.to_s }
+    def add_alias(*args)
+      args.each do |unit_alias|
+        @aliases << unit_alias.to_s
+        self.class[unit_alias] = self
+      end
     end
     
-    def convert_to(name, &block)
-      @conversions[name.to_s] = block
+    def add_conversion(unit_name, &block)
+      @conversions[unit_name.to_s] = block
     end
     
-    def conversion(name)
-      Measurement.unit(name).aliases.each do |a|
-        conversion = @conversions[a.to_s]
+    def conversion(unit_name)
+      unit = self.class[unit_name]
+      return nil unless unit
+      
+      unit.aliases.each do |unit_alias|
+        conversion = @conversions[unit_alias.to_s]
         return conversion if conversion
       end
+      
+      nil
     end
     
     def inspect
       to_s
     end
@@ -36,8 +44,41 @@
       name
     end
     
     def ==(obj)
       obj.kind_of?(self.class) && hash == obj.hash
+    end
+    
+    def self.define(unit_name, &block)
+      Builder.new(unit_name, &block)
+    end
+    
+    def self.[](unit_name)
+      @definitions[unit_name.to_s.downcase]
+    end
+    
+    private
+    
+    def self.[]=(unit_name, unit)
+      @definitions[unit_name.to_s.downcase] = unit
+    end
+    
+    class Builder
+      def initialize(unit_name, &block)
+        @unit = Unit.new(unit_name)
+        block.call(self) if block_given?
+      end
+      
+      def alias(*args)
+        @unit.add_alias(*args)
+      end
+      
+      def convert_to(unit_name, &block)
+        @unit.add_conversion(unit_name, &block)
+      end
+      
+      def to_unit
+        @unit
+      end
     end
   end
 end