MetaClass methods and properties, and listen for and respond to file modifications during development.
Plugins can also be used to modularize an application. Ordinarily, when thinking of plugins, you probably think about the hundreds of plugins that have been released to the central Grails plugin repository. These were created by community members and Grails team members to be reused by anyone who is interested, but you can create private plugins and even host your own plugin repository. If you find that you have common code that you want to share between applications, you can extract it out into a plugin and install it in all the applications that use it.
Creating a new Grails plugin is very similar to creating a Grails application, but instead of running
grails create-app <appname>, you run
grails create-plugin <pluginname> (or use your IDE). The directory structure of an application and a plugin are very similar (Figure 8-1). This is intentional, because a plugin can contribute any of the ...