How to use Sets data structure in Axapta

The Set class is used for the storage and retrieval of data from a collection in which the values of the elements contained are unique and serve as the key values according to which the data is automatically ordered.

Solution with Sets
 
Declare set in Form\class declaration

Set                         setChangedRecord;

Initialize set on Form\DataSource\init as follows:

setChangedRecord     = new Set(Types::Record);

Store records in set on Write method of the data source as follows

 if (!setChangedRecord.in(purchReqLine))
    {
        setChangedRecord.add(purchReqLine);
    }

Traversing of records in Set:

Following is the way of traversing records from Set

SetEnumerator   setEnumerator    = setChangedRecord.getEnumerator();

 while (setEnumerator.moveNext())
            {
                reqLine = setEnumerator.current();
                if (!reqLine.IsSaved)
                {
                    purchReqLineLocal = PurchReqLine::findRecId(reqLine.RecId,true);
                    purchReqLineLocal.IsSaved = true;
                    purchReqLineLocal.update();
                }

            }