module ActiveModel::AttributeMethods::ClassMethods

def alias_attribute(new_name, old_name)

person.nickname_short? # => true
person.name_short? # => true
person.nickname # => "Bob"
person.name # => "Bob"
person.name = 'Bob'
person = Person.new

end
end
send(attr).length < 5
def attribute_short?(attr)
private

alias_attribute :nickname, :name

define_attribute_methods :name
attribute_method_suffix '_short?'
attr_accessor :name

include ActiveModel::AttributeMethods
class Person

Allows you to make aliases for attributes. 
def alias_attribute(new_name, old_name)
  self.attribute_aliases = attribute_aliases.merge(new_name.to_s => old_name.to_s)
  ActiveSupport::CodeGenerator.batch(self, __FILE__, __LINE__) do |code_generator|
    attribute_method_matchers.each do |matcher|
      method_name = matcher.method_name(new_name).to_s
      target_name = matcher.method_name(old_name).to_s
      parameters = matcher.parameters
      mangled_name = target_name
      unless NAME_COMPILABLE_REGEXP.match?(target_name)
        mangled_name = "__temp__#{target_name.unpack1("h*")}"
      end
      code_generator.define_cached_method(method_name, as: mangled_name, namespace: :alias_attribute) do |batch|
        body = if CALL_COMPILABLE_REGEXP.match?(target_name)
          "self.#{target_name}(#{parameters || ''})"
        else
          call_args = [":'#{target_name}'"]
          call_args << parameters if parameters
          "send(#{call_args.join(", ")})"
        end
        modifier = matcher.parameters == FORWARD_PARAMETERS ? "ruby2_keywords " : ""
        batch <<
          "#{modifier}def #{mangled_name}(#{parameters || ''})" <<
          body <<
          "end"
      end
    end
  end
end

def attribute_alias(name)

Returns the original name for the alias +name+ 
def attribute_alias(name)
  attribute_aliases[name.to_s]
end

def attribute_alias?(new_name)

Is +new_name+ an alias? 
def attribute_alias?(new_name)
  attribute_aliases.key? new_name.to_s
end

def attribute_method_affix(*affixes)

person.name # => 'Default Name'
person.reset_name_to_default!
person.name # => 'Gem'
person = Person.new

end
end
send("#{attr}=", 'Default Name')
def reset_attribute_to_default!(attr)
private

define_attribute_methods :name
attribute_method_affix prefix: 'reset_', suffix: '_to_default!'
attr_accessor :name

include ActiveModel::AttributeMethods
class Person

accept at least the +attr+ argument.
An #{prefix}attribute#{suffix} instance method must exist and

#{prefix}attribute#{suffix}(#{attr}, *args, &block)

to

#{prefix}#{attr}#{suffix}(*args, &block)

the method.
and suffix. Uses +method_missing+ and respond_to? to rewrite
Declares a method available for all attributes with the given prefix 
def attribute_method_affix(*affixes)
  self.attribute_method_matchers += affixes.map! { |affix| AttributeMethodMatcher.new(**affix) }
  undefine_attribute_methods
end

def attribute_method_matchers_cache

this cache).
significantly (in our case our test suite finishes 10% faster with
used to alleviate the GC, which ultimately also speeds up the app
match result is always the same given a +method_name+, this cache is
object creations. Most of the time it returns a +nil+ match. As the
array doing regular expression matches, which results in a lot of
+matched_attribute_method+. The latter method iterates through an
invoked often in a typical rails, both of which invoke the method
The methods +method_missing+ and +respond_to?+ of this module are 
def attribute_method_matchers_cache
  @attribute_method_matchers_cache ||= Concurrent::Map.new(initial_capacity: 4)
end

def attribute_method_matchers_matching(method_name) 

def attribute_method_matchers_matching(method_name)
  attribute_method_matchers_cache.compute_if_absent(method_name) do
    attribute_method_matchers.filter_map { |matcher| matcher.match(method_name) }
  end
end

def attribute_method_prefix(*prefixes, parameters: nil)

person.name # => nil
person.clear_name
person.name # => "Bob"
person.name = 'Bob'
person = Person.new

end
end
send("#{attr}=", nil)
def clear_attribute(attr)
private

define_attribute_methods :name
attribute_method_prefix 'clear_'
attr_accessor :name

include ActiveModel::AttributeMethods
class Person

at least the +attr+ argument.
An instance method #{prefix}attribute must exist and accept

#{prefix}attribute(#{attr}, *args, &block)

to

#{prefix}#{attr}(*args, &block)

Uses +method_missing+ and respond_to? to rewrite the method.
Declares a method available for all attributes with the given prefix. 
def attribute_method_prefix(*prefixes, parameters: nil)
  self.attribute_method_matchers += prefixes.map! { |prefix| AttributeMethodMatcher.new(prefix: prefix, parameters: parameters) }
  undefine_attribute_methods
end

def attribute_method_suffix(*suffixes, parameters: nil)

person.name_short? # => true
person.name # => "Bob"
person.name = 'Bob'
person = Person.new

end
end
send(attr).length < 5
def attribute_short?(attr)
private

define_attribute_methods :name
attribute_method_suffix '_short?'
attr_accessor :name

include ActiveModel::AttributeMethods
class Person

least the +attr+ argument.
An attribute#{suffix} instance method must exist and accept at

attribute#{suffix}(#{attr}, *args, &block)

to

#{attr}#{suffix}(*args, &block)

Uses +method_missing+ and respond_to? to rewrite the method.
Declares a method available for all attributes with the given suffix. 
def attribute_method_suffix(*suffixes, parameters: nil)
  self.attribute_method_matchers += suffixes.map! { |suffix| AttributeMethodMatcher.new(suffix: suffix, parameters: parameters) }
  undefine_attribute_methods
end

def define_attribute_method(attr_name, _owner: generated_attribute_methods)

person.name_short? # => true
person.name # => "Bob"
person.name = 'Bob'
person = Person.new

end
end
send(attr).length < 5
def attribute_short?(attr)
private

define_attribute_method :name
# attribute_method_affix declarations.
# attribute_method_prefix, attribute_method_suffix or
# Call to define_attribute_method must appear after the

attribute_method_suffix '_short?'
attr_accessor :name

include ActiveModel::AttributeMethods
class Person

method, or they will not hook in.
+define_attribute_method+ after you define any prefix, suffix or affix
To use, pass an attribute name (as string or symbol). Be sure to declare

ActiveModel::AttributeMethods.
Declares an attribute that should be prefixed and suffixed by 
def define_attribute_method(attr_name, _owner: generated_attribute_methods)
  ActiveSupport::CodeGenerator.batch(_owner, __FILE__, __LINE__) do |owner|
    attribute_method_matchers.each do |matcher|
      method_name = matcher.method_name(attr_name)
      unless instance_method_already_implemented?(method_name)
        generate_method = "define_method_#{matcher.target}"
        if respond_to?(generate_method, true)
          send(generate_method, attr_name.to_s, owner: owner)
        else
          define_proxy_call(owner, method_name, matcher.target, matcher.parameters, attr_name.to_s, namespace: :active_model_proxy)
        end
      end
    end
    attribute_method_matchers_cache.clear
  end
end

def define_attribute_methods(*attr_names)

end
end
send("#{attr}=", nil)
def clear_attribute(attr)
private

define_attribute_methods :name, :age, :address
# attribute_method_affix declarations.
# attribute_method_prefix, attribute_method_suffix or
# Call to define_attribute_methods must appear after the

attribute_method_prefix 'clear_'
attr_accessor :name, :age, :address

include ActiveModel::AttributeMethods
class Person

methods, or they will not hook in.
+define_attribute_methods+ after you define any prefix, suffix, or affix
To use, pass attribute names (as strings or symbols). Be sure to declare

ActiveModel::AttributeMethods.
Declares the attributes that should be prefixed and suffixed by 
def define_attribute_methods(*attr_names)
  ActiveSupport::CodeGenerator.batch(generated_attribute_methods, __FILE__, __LINE__) do |owner|
    attr_names.flatten.each { |attr_name| define_attribute_method(attr_name, _owner: owner) }
  end
end

def define_proxy_call(code_generator, name, target, parameters, *call_args, namespace:)

if the called name cannot be compiled.
using the given `extra` args. This falls back on `send`
Define a method `name` in `mod` that dispatches to `send` 
def define_proxy_call(code_generator, name, target, parameters, *call_args, namespace:)
  mangled_name = name
  unless NAME_COMPILABLE_REGEXP.match?(name)
    mangled_name = "__temp__#{name.unpack1("h*")}"
  end
  code_generator.define_cached_method(name, as: mangled_name, namespace: :"#{namespace}_#{target}") do |batch|
    call_args.map!(&:inspect)
    call_args << parameters if parameters
    body = if CALL_COMPILABLE_REGEXP.match?(target)
      "self.#{target}(#{call_args.join(", ")})"
    else
      call_args.unshift(":'#{target}'")
      "send(#{call_args.join(", ")})"
    end
    modifier = parameters == FORWARD_PARAMETERS ? "ruby2_keywords " : ""
    batch <<
      "#{modifier}def #{mangled_name}(#{parameters || ''})" <<
      body <<
      "end"
  end
end

def generated_attribute_methods 

def generated_attribute_methods
  @generated_attribute_methods ||= Module.new.tap { |mod| include mod }
end

def instance_method_already_implemented?(method_name) 

def instance_method_already_implemented?(method_name)
  generated_attribute_methods.method_defined?(method_name)
end

def undefine_attribute_methods

person.name_short? # => NoMethodError

Person.undefine_attribute_methods

person.name_short? # => true
person.name = 'Bob'
person = Person.new

end
end
send(attr).length < 5
def attribute_short?(attr)
private

define_attribute_method :name
attribute_method_suffix '_short?'
attr_accessor :name

include ActiveModel::AttributeMethods
class Person

Removes all the previously dynamically defined methods from the class. 
def undefine_attribute_methods
  generated_attribute_methods.module_eval do
    undef_method(*instance_methods)
  end
  attribute_method_matchers_cache.clear
end