-module ActiveSupport
- module CoreExtensions
- module Module
- # Encapsulates the common pattern of:
- #
- # alias_method :foo_without_feature, :foo
- # alias_method :foo, :foo_with_feature
- #
- # With this, you simply do:
- #
- # alias_method_chain :foo, :feature
- #
- # And both aliases are set up for you.
- #
- # Query and bang methods (foo?, foo!) keep the same punctuation:
- #
- # alias_method_chain :foo?, :feature
- #
- # is equivalent to
- #
- # alias_method :foo_without_feature?, :foo?
- # alias_method :foo?, :foo_with_feature?
- #
- # so you can safely chain foo, foo?, and foo! with the same feature.
- def alias_method_chain(target, feature)
- # Strip out punctuation on predicates or bang methods since
- # e.g. target?_without_feature is not a valid method name.
- aliased_target, punctuation = target.to_s.sub(/([?!=])$/, ''), $1
- yield(aliased_target, punctuation) if block_given?
-
- with_method, without_method = "#{aliased_target}_with_#{feature}#{punctuation}", "#{aliased_target}_without_#{feature}#{punctuation}"
-
- alias_method without_method, target
- alias_method target, with_method
-
- case
- when public_method_defined?(without_method)
- public target
- when protected_method_defined?(without_method)
- protected target
- when private_method_defined?(without_method)
- private target
- end
- end
-
- # Allows you to make aliases for attributes, which includes
- # getter, setter, and query methods.
- #
- # Example:
- #
- # class Content < ActiveRecord::Base
- # # has a title attribute
- # end
- #
- # class Email < Content
- # alias_attribute :subject, :title
- # end
- #
- # e = Email.find(1)
- # e.title # => "Superstars"
- # e.subject # => "Superstars"
- # e.subject? # => true
- # e.subject = "Megastars"
- # e.title # => "Megastars"
- def alias_attribute(new_name, old_name)
- module_eval <<-STR, __FILE__, __LINE__+1
- def #{new_name}; self.#{old_name}; end # def subject; self.title; end
- def #{new_name}?; self.#{old_name}?; end # def subject?; self.title?; end
- def #{new_name}=(v); self.#{old_name} = v; end # def subject=(v); self.title = v; end
- STR
- end
- end
- end
-end