README.md in attribute_extras-0.0.1 vs README.md in attribute_extras-0.1.0

@@ -1,8 +1,8 @@
 ## AttributeExtras
 
-Use this gem for automatic behavior on attributes. It provides three class macros that can be used for managing attributes.
+Use this gem for automatic behavior on attributes. It by default provides three class macros that can be used for managing attributes. You can also build your own macros that will automatically become available to you within your ActiveRecord models. By default each macro gets the options `:validator` and `:writer` and both are set to true. If you do not want the macros to validate or overwrite the attribute writers, you can pass false to those options.
 
 ### nullify_attributes
 
 Causes attribute assignment to check for presence of the given value, and set the value accordingly.
 
@@ -28,21 +28,19 @@
 p.name # => 'value'
 ```
 
 ### truncate_attributes
 
-Causes string attribute assignment to be truncated down to the maximum allowed value for that column. If `whiny` is set to true, instead adds a length validator on that attribute to cause it to error if saved.
+Causes string attribute assignment to be truncated down to the maximum allowed value for that column.
 
 ```ruby
 class Person < ActiveRecord::Base
-  truncate_attributes :first_name
-  truncate_attributes :last_name, whiny: true
+  truncate_attributes :name
 end
 
-p = Person.new(first_name: 'a' * 500, last_name: 'a' * 500)
-p.first_name # => 'a' * limit
-p.save! # => ActiveRecord::RecordInvalid: Validation failed
+p = Person.new(name: 'a' * 500)
+p.name # => 'a' * limit
 ```
 
 ### Inheritance
 
 By default, attributes that you manipulate with any of the above macros will be inherited into the subclasses.
@@ -66,9 +64,32 @@
 Person.inherited_nullified_attributes.map(&:attribute) # => [:name]
 
 Developer.nullified_attributes.map(&:attribute) # => [:email]
 Developer.inherited_nullified_attributes.map(&:attribute) # => [:email, :name]
 ```
+
+## Internals
+
+If you want to register your own macros, you can do so with `AttributeExtras.register_extra`. Internally `attribute_extras` does this for the three macros listed above.
+
+### `:nullify` Example
+
+```ruby
+self.register_extra :nullify, ->(value, options){ value.presence },
+  past: :nullified,
+  validator: { format: { allow_nil: true, without: /\A\s*\z/ } }
+```
+
+### `:truncate` Example
+
+```ruby
+self.register_extra :truncate, ->(value, options){ value.is_a?(String) ? value[0...options[:limit]] : value },
+  past: :truncated,
+  validator: ->(options){ { length: { maximum: options[:limit] } } },
+  options: ->(attribute){ { limit: self.columns_hash[attribute.to_s].limit } }
+```
+
+In this case the options is needed to build a hash of metadata about the attribute in question so that the validator option can change. The options hash is also passed in to the `truncate_attribute_extra` method so that you have access to that metadata.
 
 ## Additional information
 
 ### Contributing