lazy_association.rb in shamu-0.0.24

- old
+ new
@@ -1,31 +1,63 @@
 module Shamu
   module Services
 
     # Lazily look up an associated resource
-    class LazyAssociation < Delegator
+    module LazyAssociation
+      EXCLUDE_PATTERN = /\A(block_given\?|id|send|public_send|iterator|object_id|to_model_id|binding|class|kind_of\?|is_a\?|instance_of\?|respond_to\?|p.+_methods|__.+__)\z/ # rubocop:disable Metrics/LineLength
+      MUTEX = Mutex.new
 
-      # ============================================================================
-      # @!group Attributes
-      #
+      def self.class_for( klass ) # rubocop:disable Metrics/MethodLength, Metrics/PerceivedComplexity
+        return klass.const_get( :Lazy_ ) if klass.const_defined?( :Lazy_ )
 
-      # @!attribute
-      # @return [Object] the primary key id of the association. Not delegated so
-      #     it is safe to use and will not trigger an unnecessary fetch.
-      attr_reader :id
+        MUTEX.synchronize do
 
-      #
-      # @!endgroup Attributes
+          # Check again in case another thread defined it while waiting for the
+          # mutex
+          return klass.const_get( :Lazy_ ) if klass.const_defined?( :Lazy_ )
 
-      def initialize( id, &block )
-        @id = id
-        @block = block
-      end
+          lazy_class = Class.new( klass ) do
+            # Remove all existing public methods so that they can be delegated
+            # with #method_missing.
+            klass.public_instance_methods.each do |method|
+              next if EXCLUDE_PATTERN =~ method
+              undef_method method
+            end
 
-      def __getobj__
-        return @association if defined? @association
+            def initialize( id, &block )
+              @id = id
+              @block = block
+            end
 
-        @association = @block.call
+            # @!attribute
+            # @return [Object] the primary key id of the association. Not delegated so
+            #     it is safe to use and will not trigger an unnecessary fetch.
+            attr_reader :id
+
+            def __getobj__
+              return @association if defined? @association
+
+              @association = @block.call( @id ) if @block
+            end
+
+            def method_missing( method, *args, &block )
+              if respond_to_missing?( method )
+                __getobj__.public_send( method, *args, &block )
+              else
+                super
+              end
+            end
+
+            def respond_to_missing?( method, include_private = false )
+              __getobj__.respond_to?( method, include_private ) || super
+            end
+
+          end
+
+          klass.const_set( :Lazy_, lazy_class )
+          lazy_class
+        end
       end
+
     end
   end
-end
\ No newline at end of file
+end