Make Error a component.

lib/simple_form/abstract_component.rb

@@ -0,0 +1,32 @@
+module SimpleForm
+  class AbstractComponent
+    attr_reader :builder, :attribute, :input_type, :options
+
+    def initialize(builder, attribute, input_type, options)
+      @builder    = builder
+      @attribute  = attribute
+      @input_type = input_type
+      @options    = options 
+    end
+
+    def generate
+      (valid? ? content : nil).to_s
+    end
+
+    def valid?
+      true
+    end
+
+    def template
+      @builder.template
+    end
+
+    def object
+      @builder.object
+    end
+
+    def hidden_input?
+      @input_type == :hidden
+    end
+  end
+end

lib/simple_form/error.rb

@@ -1,20 +1,15 @@
 module SimpleForm
-  module Error
+  class Error < AbstractComponent
+    def valid?
+      !hidden_input? && !errors.blank?
+    end
 
-    private
+    def errors
+      @errors ||= object.errors[@attribute]
+    end
 
-      def generate_error
-        return '' if skip_error? || (errors = find_errors).blank?
-        errors = errors.to_sentence if errors.respond_to?(:to_sentence)
-        @template.content_tag(:span, errors, :class => 'error')
-      end
-
-      def skip_error?
-        hidden_input?
-      end
-
-      def find_errors
-        @object.errors[@attribute]
-      end
+    def content
+      template.content_tag(:span, Array(errors).to_sentence, :class => 'error')
+    end
   end
 end

lib/simple_form/form_builder.rb

@@ -1,3 +1,5 @@
+require 'simple_form/abstract_component'
+
 require 'simple_form/label'
 require 'simple_form/input'
 require 'simple_form/hint'
@@ -7,10 +9,12 @@ require 'simple_form/i18n_cache'
 
 module SimpleForm
   class FormBuilder < ActionView::Helpers::FormBuilder
+    # Make the template accessible for components
+    attr_reader :template
+
     include SimpleForm::Label
     include SimpleForm::Input
     include SimpleForm::Hint
-    include SimpleForm::Error
 
     extend SimpleForm::MapType
     extend SimpleForm::I18nCache
@@ -37,7 +41,7 @@ module SimpleForm
       label = generate_label
       input = generate_input
       hint  = generate_hint
-      error = generate_error
+      error = Error.new(self, @attribute, @input_type, @options).generate
 
       label << input << hint << error
     end