The Quest for an ObjectScript Iterator (part 5)

In which we take the last post's iterator and simply wrap it inside a Caché Objects class.

Define a class User.MultiIterator

Class User.MultiIterator Extends %Persistent
{

Property i As %String;
Property j As %String;
Property k As %String;
Property val As %String;

Method startIterator()
{
  set ..i=""
  set ..j=""
  set ..k=""
}

Method next()
{
  if (..i="") {
    set ..i=$order(^multi(..i))
    quit ..next()
  }
  if (..j="") {
    set ..j=$order(^multi(..i,..j))
    quit ..next()
  }
  set ..k=$order(^multi(..i,..j,..k))
  if ..k'="" {
    set ..val = $get(^multi(..i,..j,..k))
    quit 1
  }
  set ..j=$order(^multi(..i,..j))
  if ..j'="" {
    quit ..next()
  }
  set ..i=$order(^multi(..i))
  if ..i'="" {
    quit ..next()
  }
  quit 0
}

}

Using it (in another file) is now :

new it
set it= ##class(User.MultiIterator).%New()
do it.startIterator()
while it.next() {
  write !,it.i_","_it.j_","_it.k_" : "_it.val
}

The logic is identical. The only difference, now I've made the i,j and k indices and the val properties of the iterator object rather than local variables passed by reference. It looks perhaps a little cleaner from the user's perspective. OTOH you have to create an extra class definition routine.

In the next post I think it's time to start thinking how we can add some filtering to the iterator.

Update : thanks to 80N for the correct. (Read comments)