annotations - Using scala constants in constant expressions -

i have constants, made of other, smaller constants. example

object myconstants {     final val tablename = "table_name";     final val fieldname = "field_name";     final val indexname = tablename + "_" + fieldname + "_ix"; // 1 not want constant } 

i want these true constants because use them in annotations.

how make work? (on scala 2.11)

what want

interface myconstants {     string tablename = "table_name";     string fieldname = "field_name";     string indexname = tablename + "_" + fieldname + "_ix"; } 

but in scala. scalac not pick constants usage in annotations if compiles them java class/interface (see si-5333) decided put them in scala object. works literals, , expressions literals, not expressions other constants.

with code:

import javax.persistence.entity import javax.persistence.table import org.hibernate.annotations.index  object myconstants {     final val tablename = "table_name";     final val fieldname = "field_name";     final val indexname = tablename + "_" + fieldname + "_ix"; }  @entity @table(name = myconstants.tablename) @org.hibernate.annotations.table(     appliesto = myconstants.tablename,     indexes = array(new index(name = myconstants.indexname, columnnames = array(myconstants.fieldname))))  class myentity { } 

i following error on line indexes = ...

annotation argument needs constant; found: myconstants.indexname

edit: after fiddling around few build configurations, think scala-ide specific issue. code indeed compile alright when build project gradle or sbt. use build tool actual projects, in end it's having few incomprehensible markers in ide - annoying, has little functionality.

i used constants in jpa scala. code compiles, , used it:

freedays.scala

@entity @table(name = "free_days") @namedqueries(   array(     new namedquery(name = jpaqueries.is_free_days, query = "select f freedays f f.dateoffreeday = :" + jpaqueries.date)   ) ) class freedays {    def this(id: int, name: string, dateoffreeday: date) = {     this()     this.id = id     this.name = name     this.dateoffreeday = dateoffreeday   }    @id   @generatedvalue   var id: long = _    var name: string = _    @column(name = "date_of_free_day")   @temporal(temporaltype.date)   var dateoffreeday: date = _ } 

jpaqueries.scala

object jpaqueries extends jpaqueries  sealed trait jpaqueries {   final val is_free_days = "is_free_days"   final val date = "date" }