class Rails::Generators::Base

def self.default_source_root

root, you should use source_root.
by rails to set its generators source root. If you want to customize your source
Returns the default source root for a given generator. This is used internally 
def self.default_source_root
  return unless base_name && generator_name
  path = File.expand_path(File.join(base_name, generator_name, 'templates'), base_root)
  path if File.exists?(path)
end