redmine/lib/redmine/subclass_factory.rb

# Redmine - project management software
# Copyright (C) 2006-2017  Jean-Philippe Lang
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

module Redmine
  module SubclassFactory
    def self.included(base)
      base.extend ClassMethods
    end

    module ClassMethods
      def get_subclass(class_name)
        klass = nil
        begin
          klass = class_name.to_s.classify.constantize
        rescue
          # invalid class name
        end
        unless subclasses.include? klass
          klass = nil
        end
        klass
      end

      # Returns an instance of the given subclass name
      def new_subclass_instance(class_name, *args)
        klass = get_subclass(class_name)
        if klass
          klass.new(*args)
        end
      end
    end
  end
end