diff options
Diffstat (limited to 'activesupport/lib/active_support/deprecation/constant_accessor.rb')
| -rw-r--r-- | activesupport/lib/active_support/deprecation/constant_accessor.rb | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/deprecation/constant_accessor.rb b/activesupport/lib/active_support/deprecation/constant_accessor.rb new file mode 100644 index 0000000000..2b19de365f --- /dev/null +++ b/activesupport/lib/active_support/deprecation/constant_accessor.rb @@ -0,0 +1,50 @@ +require "active_support/inflector/methods" + +module ActiveSupport + class Deprecation + # DeprecatedConstantAccessor transforms a constant into a deprecated one by + # hooking +const_missing+. + # + # 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 same object as the new one rather + # than a proxy object, so it can be used transparently in +rescue+ blocks + # etc. + # + # 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) + # include ActiveSupport::Deprecation::DeprecatedConstantAccessor + # deprecate_constant '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"] + module DeprecatedConstantAccessor + def self.included(base) + extension = Module.new do + def const_missing(missing_const_name) + if class_variable_defined?(:@@_deprecated_constants) + if (replacement = class_variable_get(:@@_deprecated_constants)[missing_const_name.to_s]) + replacement[:deprecator].warn(replacement[:message] || "#{name}::#{missing_const_name} is deprecated! Use #{replacement[:new]} instead.", caller_locations) + return ActiveSupport::Inflector.constantize(replacement[:new].to_s) + end + end + super + end + + def deprecate_constant(const_name, new_constant, message: nil, deprecator: ActiveSupport::Deprecation.instance) + class_variable_set(:@@_deprecated_constants, {}) unless class_variable_defined?(:@@_deprecated_constants) + class_variable_get(:@@_deprecated_constants)[const_name.to_s] = { new: new_constant, message: message, deprecator: deprecator } + end + end + base.singleton_class.prepend extension + end + end + end +end |