| [#47] | project: specification | priority: low | category: missing feature | |
|---|---|---|---|---|
| submitter | assigned to | status | date submitted | |
| Burak | Martin | open | 2003-06-27 12:24:12.0 | |
| subject | Constr( T* ) not 1st class | |||
| code |
// this is not possible
MySuperXML_Tag( children: Elem* ) extends Elem;
factory = new HashMap( String, Elem* => Elem )
factory.put("MySuperXML_Tag", MySuperXML_Tag )
// ^
// error "methods with repeated args have to be
// fully applied" |
|||
| what happened | if you have a constructor with "repeated parameters", then it is not possible to use the constructor as a value,\ like above. The dtd-import tool + parser interface critically depend on 1st class constructors, because you decide on runtime, which class to construct. |
|||
| what expected | To be able to use MySuperXML_Tag as if it was a constructor My...( children:Seq[Elem] ) | |||
| [back to overview] | ||||
| Matthias edited on 2003-06-27 12:24:12.0 |
| I have the strong feeling that currently, classes with such constructors can only be used in a very limited form. In particular, you can only construct objects of such classes if you statically know all the elements you want to pass to the constructor. If you just have a variable that contains the elements, you are out of luck... Maybe we should rethink what we want to achieve with such classes. |
| Martin edited on 2003-07-10 15:43:00.0 |
| Burak edited on 2003-09-23 18:30:32.0 |
| Lex edited on 2006-03-28 14:02:44.0 |
Here's a cleaned up version of the proposal:
import scala.collection.mutable.HashMap
object Test {
case class MySuperXML_Tag( children: Any* )
val factory = new HashMap[String, Any* => Any ]
factory("MySuperXML_Tag") = MySuperXML_Tag
}
It still is not implemented. Additionally, it is not allowed to change the HashMap to use Seq[Any], either: val factory = new HashMap[String, Seq[Any] => Any ] It strikes me that it would be nice to have some way to refer to MySuperXML_Tag as a value.... Either * types should be allowed in functions, or there should be a conversion available from embedded * types to Seq types. |