Improve IntrinsicFuncion.new

lib/floe/workflow/intrinsic_function.rb

@@ -6,7 +6,15 @@ class IntrinsicFunction
       INTRINSIC_FUNCTION_REGEX = /^(?<module>\w+)\.(?<function>\w+)\((?<args>.*)\)$/.freeze
 
       class << self
-        def klass(payload)
+        def new(*args)
+          if self == Floe::Workflow::IntrinsicFunction
+            detect_class(*args).new(*args)
+          else
+            super
+          end
+        end
+
+        private def detect_class(payload)
           function_module_name, function_name =
             payload.match(INTRINSIC_FUNCTION_REGEX)
                    .named_captures
@@ -23,16 +31,6 @@ def klass(payload)
         def value(payload, context, input = {})
           new(payload).value(context, input)
         end
-
-        private alias_method :orig_new, :new
-
-        def new(*args)
-          if self == Floe::Workflow::IntrinsicFunction
-            klass(*args).new(*args)
-          else
-            orig_new(*args)
-          end
-        end
       end
 
       attr_reader :args

spec/workflow/intrinsic_function_spec.rb

@@ -1,23 +1,19 @@
 RSpec.describe Floe::Workflow::IntrinsicFunction do
-  describe ".klass" do
-    it "returns the intrinsic function class" do
-      payload = "States.StringToJson('{\"number\": 20}')"
-      expect(described_class.klass(payload)).to eq(Floe::Workflow::IntrinsicFunctions::States::StringToJson)
-    end
-
-    it "raises an exception for an invalid intrinsic function" do
-      payload = "States.MyFirstFunction()"
-      expect { described_class.klass(payload) }.to raise_error(NotImplementedError)
-    end
-  end
-
   describe "#initialize" do
     let(:payload) { "States.StringToJson()" }
 
     it "returns an instance of the intrinsic function" do
       expect(described_class.new(payload)).to be_kind_of(Floe::Workflow::IntrinsicFunctions::States::StringToJson)
     end
 
+    context "with an invalid intrinsic function" do
+      let(:payload) { "States.MyFirstFunction()" }
+
+      it "raises an exception for an invalid intrinsic function" do
+        expect { described_class.new(payload) }.to raise_error(NotImplementedError)
+      end
+    end
+
     context "with no arguments" do
       it "parses args as empty" do
         function = described_class.new(payload)