example implementation

lib/active_interaction/base.rb

@@ -109,6 +109,23 @@ def add_filter(klass, name, options, &block)
         initialize_filter(klass.new(name, options, &block))
       end
 
+      # @since 2.0.0
+      def proxy(name, inputs)
+        (@_proxies ||= Set.new).add(name)
+
+        attr_reader name
+
+        inputs.each do |input|
+          define_method(input) do
+            send(name).send(input)
+          end
+
+          define_method("#{input}=") do |value|
+            send(name).send("#{input}=", value)
+          end
+        end
+      end
+
       # Import filters from another interaction.
       #
       # @param klass [Class] The other interaction.
@@ -156,6 +173,7 @@ def initialize_filter(filter)
     def initialize(inputs = {})
       fail ArgumentError, 'inputs must be a hash' unless inputs.is_a?(Hash)
 
+      process_proxies(self.class.instance_variable_get(:@_proxies) || Set.new)
       process_inputs(inputs.symbolize_keys)
     end
 
@@ -254,5 +272,12 @@ def type_check
         end
       end
     end
+
+    def process_proxies(proxies)
+      proxies.each do |name|
+        klass = name.to_s.camelize.constantize.new
+        instance_variable_set("@#{name}", klass)
+      end
+    end
   end
 end

lib/active_interaction/concerns/runnable.rb

@@ -52,24 +52,6 @@ def valid?(*)
       super
     end
 
-    private
-
-    # @param other [Class] The other interaction.
-    # @param (see ClassMethods.run)
-    #
-    # @return (see #result)
-    #
-    # @raise [Interrupt]
-    def compose(other, *args)
-      outcome = other.run(*args)
-
-      if outcome.valid?
-        outcome.result
-      else
-        fail Interrupt, outcome
-      end
-    end
-
     # @return (see #result=)
     # @return [nil]
     def run
@@ -83,12 +65,6 @@ def run
         end
     end
 
-    def merge_errors_onto_base(new_errors)
-      new_errors.full_messages.each do |message|
-        errors.add(:base, message) unless errors.added?(:base, message)
-      end
-    end
-
     # @return [Object]
     #
     # @raise [InvalidInteractionError] If there are validation errors.
@@ -102,6 +78,30 @@ def run!
       end
     end
 
+    private
+
+    # @param other [Class] The other interaction.
+    # @param (see ClassMethods.run)
+    #
+    # @return (see #result)
+    #
+    # @raise [Interrupt]
+    def compose(other, *args)
+      outcome = other.run(*args)
+
+      if outcome.valid?
+        outcome.result
+      else
+        fail Interrupt, outcome
+      end
+    end
+
+    def merge_errors_onto_base(new_errors)
+      new_errors.full_messages.each do |message|
+        errors.add(:base, message) unless errors.added?(:base, message)
+      end
+    end
+
     #
     module ClassMethods
       def new(*)

spec/active_interaction/base_spec.rb

@@ -18,6 +18,16 @@ def execute
   end
 end
 
+ProxyInteraction = Class.new(TestInteraction) do
+  float :x, :y
+
+  proxy :add_interaction, %i[x y]
+
+  def execute
+    add_interaction.run!
+  end
+end
+
 InterruptInteraction = Class.new(TestInteraction) do
   model :x, :y,
     class: Object,
@@ -347,6 +357,17 @@ def execute
     end
   end
 
+  describe '#proxy' do
+    let(:described_class) { ProxyInteraction }
+    let(:x) { rand }
+    let(:y) { rand }
+    let(:inputs) { { x: x, y: y } }
+
+    it 'works' do
+      expect(result).to eql x + y
+    end
+  end
+
   describe '#compose' do
     let(:described_class) { InterruptInteraction }
     let(:x) { rand }