gistfile1.rb

# Custom types are scoped to a particular site instance,
# so their class names are suffixed with the site ID.
# This also helps Content#const_missing figure out when we're
# trying to load a custom type, because it gets numbers at the
# end of the class name.
# Note: I've put some validation logic in CustomType to ensure
# that the name in the database is a valid Ruby constant name.

# new_custom_type = Content::CustomType.create(:site_id => 1, :name => "My custom type")
# Content::MyCustomType1 #=> Content::MyCustomType1(...)

module Content
  # ...
  
  def self.const_missing(sym)
    if sym.to_s =~ /\A([A-Z][a-zA-Z]*)(\d+)\z/ and custom_type = CustomType.find_by_name_and_site_id($1, $2)
      custom_type.to_class
    else
      super
    end
  end
end