ドメインクラスにパッケージを指定しようという話

Grails Tip of the Day: Always use packages

grails1.1からCategoryというドメインクラスを作ると起動時にエラーになるようです。

WindowsXP + groovy-1.6.0 + grails1.1で試したところ確かにエラーに。

Environment set to development
  [groovyc] Compiling 2 source files to C:\Documents and Settings\yuhei0718\.grails\1.1\projects\test\classes
  [groovyc] org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed, C:\Users\yuhei0718\work\grailsWork\test\grails
-app\controllers\CategoryController.groovy: 84: You cannot create an instance from the abstract interface 'groovy.lang.Category'.
  [groovyc]  @ line 84, column 32.
  [groovyc]            def categoryInstance = new Category()
  [groovyc]                                   ^
  [groovyc] C:\Users\yuhei0718\work\grailsWork\test\grails-app\controllers\CategoryController.groovy: 90: You cannot create an instance fr
om the abstract interface 'groovy.lang.Category'.
  [groovyc]  @ line 90, column 32.
  [groovyc]            def categoryInstance = new Category(params)
  [groovyc]                                   ^
  [groovyc] C:\Users\yuhei0718\work\grailsWork\test\grails-app\controllers\CategoryController.groovy: 84: You cannot create an instance fr
om the abstract interface 'groovy.lang.Category'.
  [groovyc]  @ line 84, column 32.
  [groovyc]            def categoryInstance = new Category()
  [groovyc]                                   ^
  [groovyc] C:\Users\yuhei0718\work\grailsWork\test\grails-app\controllers\CategoryController.groovy: 90: You cannot create an instance fr
om the abstract interface 'groovy.lang.Category'.
  [groovyc]  @ line 90, column 32.
  [groovyc]            def categoryInstance = new Category(params)
  [groovyc]                                   ^
  [groovyc] C:\Users\yuhei0718\work\grailsWork\test\grails-app\controllers\CategoryController.groovy: 84: You cannot create an instance fr
om the abstract interface 'groovy.lang.Category'.
  [groovyc]  @ line 84, column 32.
  [groovyc]            def categoryInstance = new Category()
  [groovyc]                                   ^
  [groovyc] C:\Users\yuhei0718\work\grailsWork\test\grails-app\controllers\CategoryController.groovy: 90: You cannot create an instance fr
om the abstract interface 'groovy.lang.Category'.
  [groovyc]  @ line 90, column 32.
  [groovyc]            def categoryInstance = new Category(params)
  [groovyc]                                   ^
  [groovyc]
  [groovyc] 6 errors
Compilation error: Compilation Failed

grails-1.0.4だと問題なく起動しました。

原文にあるとおり

grails create-domain-class  org.company.Category

とかにすればＯＫでした。
categoryとか結構チュートリアル的なサンプルで作りそうなドメインなので、古い資料でgrailsは1.1なんて状態だと
はまる人いるかもしれない。