Use the new components builder syntax.

lib/simple_form.rb

@@ -116,6 +116,20 @@ module SimpleForm
     yield self
   end
 
+  def self.components(options={})
+    builder = SimpleForm::Wrappers::Builder.new
+    yield builder
+    self.wrapper = SimpleForm::Wrappers::Root.new(builder.to_a, options)
+  end
+
+  components :tag => :div, :class => :input, :error_class => :field_with_errors do |b|
+    b.use :placeholder
+    b.use :maxlength
+    b.use :label_input
+    b.use :hint,  :tag => :span, :class => :hint
+    b.use :error, :tag => :span, :class => :error
+  end
+
   ## DEPRECATED METHODS SINCE 2.0
 
   # Default tag used on hints.
@@ -146,6 +160,7 @@ module SimpleForm
   mattr_accessor :wrapper_error_class
   @@wrapper_error_class = :field_with_errors
 
+  # Define new components using the old array syntax.
   def self.components=(array)
     self.wrapper = Wrappers::Root.new(
       array.map do |item|
@@ -163,7 +178,4 @@ module SimpleForm
       :error_class => SimpleForm.wrapper_error_class
     )
   end
-
-  # Components used by the form builder.
-  self.components = [ :placeholder, :label_input, :hint, :error ]
 end

lib/simple_form/wrappers.rb

@@ -1,5 +1,6 @@
 module SimpleForm
   module Wrappers
+    autoload :Builder,   'simple_form/wrappers/builder'
     autoload :Many,      'simple_form/wrappers/many'
     autoload :Root,      'simple_form/wrappers/root'
     autoload :Single,    'simple_form/wrappers/single'

lib/simple_form/wrappers/builder.rb

@@ -0,0 +1,51 @@
+module SimpleForm
+  module Wrappers
+    # Provides the builder syntax for components. The builder provides
+    # only one method (called `use`) and it allows the following invocations:
+    #
+    #     config.components do |b|
+    #       # Use a single component
+    #       b.use :placeholder
+    #
+    #       # Use a component with specific wrapper options
+    #       b.use :error, :tag => "span", :class => "error"
+    #
+    #       # Use a set of components by wrapping them in a tag+class.
+    #       b.use :tag => "div", :class => "another" do |ba|
+    #         ba.use :label
+    #         ba.use :input
+    #       end
+    #
+    #       # Use a set of components by wrapping them in a tag+class.
+    #       # This wrapper is identified by :label_input, which means it can
+    #       # be turned off on demand with `f.input :name, :label_input => false`
+    #       b.use :label_input, :tag => "div", :class => "another" do |ba|
+    #         ba.use :label
+    #         ba.use :input
+    #       end
+    #     end
+    #
+    class Builder
+      def initialize
+        @components = []
+      end
+
+      def use(name, options=nil)
+        if block_given?
+          name, options = nil, name if name.is_a?(Hash)
+          builder = self.class.new
+          yield builder
+          @components << Many.new(name, builder.to_a, options || {})
+        elsif options
+          @components << Single.new(name, options)
+        else
+          @components << name
+        end
+      end
+
+      def to_a
+        @components
+      end
+    end
+  end
+end