DeprecatedConstantProxy transforms a constant into a deprecated one. It takes the names of an old (deprecated) constant and of a new constant (both in string form) and optionally a deprecator. The deprecator defaults to ActiveSupport::Deprecator if none is specified. The deprecated constant now returns the value of the new one.

PLANETS = %w(mercury venus earth mars jupiter saturn uranus neptune pluto)

# (In a later update, the original implementation of `PLANETS` has been removed.)

PLANETS_POST_2006 = %w(mercury venus earth mars jupiter saturn uranus neptune)
PLANETS = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('PLANETS', 'PLANETS_POST_2006')

PLANETS.map { |planet| planet.capitalize }
# => DEPRECATION WARNING: PLANETS is deprecated! Use PLANETS_POST_2006 instead.
     (Backtrace information…)
     ["Mercury", "Venus", "Earth", "Mars", "Jupiter", "Saturn", "Uranus", "Neptune"]

Methods

Class Public methods

new(old_const, new_const, deprecator = ActiveSupport::Deprecation.instance, message: "#{old_const} is deprecated! Use #{new_const} instead.")

📝 Source code 
# File activesupport/lib/active_support/deprecation/proxy_wrappers.rb, line 126
      def initialize(old_const, new_const, deprecator = ActiveSupport::Deprecation.instance, message: "#{old_const} is deprecated! Use #{new_const} instead.")
        require "active_support/inflector/methods"

        @old_const = old_const
        @new_const = new_const
        @deprecator = deprecator
        @message = message
      end
🔎 See on GitHub

Instance Public methods

class()

Returns the class of the new constant.

PLANETS_POST_2006 = %w(mercury venus earth mars jupiter saturn uranus neptune)
PLANETS = ActiveSupport::Deprecation::DeprecatedConstantProxy.new('PLANETS', 'PLANETS_POST_2006')
PLANETS.class # => Array
📝 Source code 
# File activesupport/lib/active_support/deprecation/proxy_wrappers.rb, line 140
      def class
        target.class
      end
🔎 See on GitHub