Find all classes in a directory

find_all_classes_in_a_directory.rb

# in order to support convention over configuration it can be useful to be able to find all the classes in a directory or 
# subdirectory. This lets you have easy factories for subclasses in Rails.
# Requires that you are using Zeitwerk naming conventions for files and classes

class YourRootClass
  # this does not work with rails because although the paths are autoloaded
  # the objects are not in memory (and are only in memory when instantiated)
  # and self.inherited is only called when the classes are put in memory
  # note: this likely happens in production but not in development
  # def self.inherited(klass)
  #   @descendants ||= []
  #   @descendants << klass
  # end

  # def self.descendants
  #   @descendants || []
  # end

  def self.descendants
    result = []
    model_dir = Rails.root.join("app","models") # wherever you are keeping your root class
    processor_files = File.join("type_form","processors","*.rb") # the sub dir
    Dir.glob(processor_files, base: model_dir).each do |filename|
      filename = filename.gsub(".rb","") #remove the extension
      klass = Kernel.const_get(filename.camelize)
      result << klass
    end
    result
  end