lib/arc-furnace/abstract_join.rb in arc-furnace-0.1.3 vs lib/arc-furnace/abstract_join.rb in arc-furnace-0.1.4

@@ -1,11 +1,10 @@
 require 'arc-furnace/source'
 
 module ArcFurnace
   class AbstractJoin < Source
     private_attr_reader :hash, :source, :key_column
-    attr_reader :value
 
     # The source is a source, the hash is a hash, and one can optionally
     # pass the key column to get the primary key for each source entity, the
     # default is equijoin semantics--the key of the hash is used.
     def initialize(source: , hash:, key_column: nil)
@@ -16,12 +15,16 @@
       else
         raise 'Must be passed one Hash and one Source!'
       end
     end
 
-    def prepare
-      advance
+    def value
+      if @value.nil? && !empty?
+        advance
+      end
+      @value
     end
+
 
     def advance
       raise "Unimplemented!"
     end