Various extensions for the Ruby core Module class.
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"
# File lib/active_support/core_ext/module/aliasing.rb, line 65 def alias_attribute(new_name, old_name) module_eval 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, __FILE__, __LINE__ + 1 end
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.
# File lib/active_support/core_ext/module/aliasing.rb, line 25 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
Returns the names of the constants defined locally rather than the constants themselves. See local_constants.
# File lib/active_support/core_ext/module/introspection.rb, line 85 def local_constant_names local_constants.map { |c| c.to_s } end
Returns the constants that have been defined locally by this object and not in an ancestor. This method is exact if running under Ruby 1.9. In previous versions it may miss some constants if their definition in some ancestor is identical to their definition in the receiver.
# File lib/active_support/core_ext/module/introspection.rb, line 65 def local_constants inherited = {} ancestors.each do |anc| next if anc == self anc.constants.each { |const| inherited[const] = anc.const_get(const) } end constants.select do |const| !inherited.key?(const) || inherited[const].object_id != const_get(const).object_id end end
Returns an ActiveSupport::ModelName object for module. It can be used to retrieve all kinds of naming-related information.
# File lib/active_support/core_ext/module/model_naming.rb, line 20 def model_name @model_name ||= ::ActiveSupport::ModelName.new(name) end
Returns the module which contains this one according to its name.
module M module N end end X = M::N p M::N.parent # => M p X.parent # => M
The parent of top-level and anonymous modules is Object.
p M.parent # => Object p Module.new.parent # => Object
# File lib/active_support/core_ext/module/introspection.rb, line 30 def parent parent_name ? parent_name.constantize : Object end
Returns the name of the module containing this one.
p M::N.parent_name # => "M"
# File lib/active_support/core_ext/module/introspection.rb, line 7 def parent_name unless defined? @parent_name @parent_name = name =~ /::[^:]+\Z/ ? $`.freeze : nil end @parent_name end
Returns all the parents of this module according to its name, ordered from nested outwards. The receiver is not contained within the result.
module M module N end end X = M::N p M.parents # => [Object] p M::N.parents # => [M, Object] p X.parents # => [M, Object]
# File lib/active_support/core_ext/module/introspection.rb, line 47 def parents parents = [] if parent_name parts = parent_name.split('::') until parts.empty? parents << (parts * '::').constantize parts.pop end end parents << Object unless parents.include? Object parents end
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