```ruby
require 'dm-core'
require 'dm-is-read_only/is/read_only'
require 'dm-is-read_only/is/version'
```

Use DataMapper::Model.append_extension to register the plugin.
user
```ruby
require 'dm-core'
require 'dm-is-read_only/is/read_only'
require 'dm-is-read_only/is/version'

DataMapper::Model.append_extensions DataMapper::Is::ReadOnly
```
assistant