module LittleGhost::Support::ClassAttributes

ClassAttributes gives framework extension classes small, thread-safe, inheritable settings. A subclass inherits a value until it assigns its own; mutable defaults are not duplicated automatically.

Public Instance Methods

class_attribute (*names, default: nil)

Source

# File lib/little_ghost/support/class_attributes.rb, line 14
def class_attribute(*names, default: nil)
  names.each do |name|
    unless name.is_a?(String) || name.is_a?(Symbol)
      raise TypeError, "#{name.inspect} is not a symbol nor a string"
    end

    name = name.to_sym
    singleton_class.remove_method(name) if singleton_class.method_defined?(name, false)
    writer = :"#{name}="
    singleton_class.remove_method(writer) if singleton_class.method_defined?(writer, false)
    values = {self => default}
    mutex = Mutex.new
    define_singleton_method(name) do
      found, value = mutex.synchronize { [values.key?(self), values[self]] }
      return value if found

      superclass.public_send(name)
    end
    define_singleton_method(writer) do |value|
      mutex.synchronize { values[self] = value }
      value
    end
  end
end

Defines thread-safe singleton readers and writers for names.