module ActiveSupport::Deprecation::MethodWrapper

# File activesupport/lib/active_support/deprecation/method_wrappers.rb, line 52
def deprecate_methods(target_module, *method_names)
  options = method_names.extract_options!
  deprecator = options.delete(:deprecator) || self
  method_names += options.keys

  method_names.each do |method_name|
    aliased_method, punctuation = method_name.to_s.sub(/([?!=])$/, ""), $1
    with_method = "#{aliased_method}_with_deprecation#{punctuation}"
    without_method = "#{aliased_method}_without_deprecation#{punctuation}"

    target_module.send(:define_method, with_method) do |*args, &block|
      deprecator.deprecation_warning(method_name, options[method_name])
      send(without_method, *args, &block)
    end

    target_module.send(:alias_method, without_method, method_name)
    target_module.send(:alias_method, method_name, with_method)

    case
    when target_module.protected_method_defined?(without_method)
      target_module.send(:protected, method_name)
    when target_module.private_method_defined?(without_method)
      target_module.send(:private, method_name)
    end
  end
end

Declare that a method has been deprecated.

class Fred
  def aaa; end
  def bbb; end
  def ccc; end
  def ddd; end
  def eee; end
end

Using the default deprecator:

ActiveSupport::Deprecation.deprecate_methods(Fred, :aaa, bbb: :zzz, ccc: 'use Bar#ccc instead')
# => Fred

Fred.new.aaa
# DEPRECATION WARNING: aaa is deprecated and will be removed from Rails 5.1. (called from irb_binding at (irb):10)
# => nil

Fred.new.bbb
# DEPRECATION WARNING: bbb is deprecated and will be removed from Rails 5.1 (use zzz instead). (called from irb_binding at (irb):11)
# => nil

Fred.new.ccc
# DEPRECATION WARNING: ccc is deprecated and will be removed from Rails 5.1 (use Bar#ccc instead). (called from irb_binding at (irb):12)
# => nil

Passing in a custom deprecator:

custom_deprecator = ActiveSupport::Deprecation.new('next-release', 'MyGem')
ActiveSupport::Deprecation.deprecate_methods(Fred, ddd: :zzz, deprecator: custom_deprecator)
# => [:ddd]

Fred.new.ddd
DEPRECATION WARNING: ddd is deprecated and will be removed from MyGem next-release (use zzz instead). (called from irb_binding at (irb):15)
# => nil

Using a custom deprecator directly:

custom_deprecator = ActiveSupport::Deprecation.new('next-release', 'MyGem')
custom_deprecator.deprecate_methods(Fred, eee: :zzz)
# => [:eee]

Fred.new.eee
DEPRECATION WARNING: eee is deprecated and will be removed from MyGem next-release (use zzz instead). (called from irb_binding at (irb):18)
# => nil