Added the ability to reference methods within the builder block that hav...

lib/halibut/builder.rb

@@ -1,4 +1,5 @@
 require 'halibut/core/resource'
+require 'halibut/dsl'
 
 module Halibut
 
@@ -28,10 +29,11 @@ def resource
     #
     class RootContext
 
+      include DSL
+
       def initialize(resource, &blk)
         @resource = resource
-
-        instance_eval(&blk) if block_given?
+        instance_eval_with_previous_context_available(&blk) if block_given?
       end
 
       # Sets a property on the resource.
@@ -108,11 +110,13 @@ def relation(rel, &blk)
 
     class RelationContext
 
+      include DSL
+
       def initialize(resource, rel, &blk)
         @resource = resource
         @rel      = rel
 
-        instance_eval(&blk) if block_given?
+        instance_eval_with_previous_context_available(&blk) if block_given?
       end
 
       def link(href, opts={})

lib/halibut/dsl.rb

@@ -0,0 +1,61 @@
+module Halibut
+
+  module DSL
+
+    def instance_eval_with_previous_context_available(*args, &block)
+      DslDelegator.new(self).instance_eval_with_previous_context_available(&block)
+    end
+
+    class DslDelegator
+
+      def initialize delegation_target
+        @delegation_target = delegation_target
+      end
+
+      def instance_eval_with_previous_context_available(*args, &block)
+        with_previous_context_available(block.binding) do
+          bind_block_as_instance_method_on_self(&block).call(*args)
+        end
+      end
+
+      protected
+
+      def method_missing(method, *args, &block)
+        if delegation_target_responds_to? method
+          delegation_target.send(method, *args, &block)
+        else
+          previous_context.send(method, *args, &block)
+        end
+      end
+
+      private
+
+      attr_accessor :delegation_target, :previous_context
+
+      def bind_block_as_instance_method_on_self(&block)
+        create_instance_method_from_block(&block).bind(self)
+      end
+
+      def create_instance_method_from_block &block
+        meth = self.class.class_eval do
+          define_method :___block_as_instance_method_, &block
+          meth = instance_method :___block_as_instance_method_
+          remove_method :___block_as_instance_method_
+          meth
+        end
+      end
+
+      def with_previous_context_available(binding, &block)
+        @previous_context = binding.eval('self')
+        result = block.call
+        @previous_context = nil
+        result
+      end
+
+      def delegation_target_responds_to?(method)
+        delegation_target.respond_to? method
+      end
+
+    end
+  end
+end

spec/builder_spec.rb

@@ -179,4 +179,22 @@
     end
   end
 
+  describe "Using methods declared outside the builder" do
+    it "evaluates the methods in the context of the block's declaration scope" do
+      def local_method
+        'bar'
+      end
+
+      builder = Halibut::Builder.new do
+        property 'foo', local_method
+      end
+
+      resource = Halibut::Core::Resource.new
+      resource.set_property 'foo', local_method
+
+      builder.resource.properties['foo'].must_equal local_method
+      builder.resource.must_equal resource, diff(builder.resource.to_hash, resource.to_hash)
+    end
+  end
+
 end