private Object executePlus(PageContext pc,SQL sql,Query qr,ZExpression expression,int row) throws PageException {
  Object left=executeExp(pc,sql,qr,expression.getOperand(0),row);
  Object right=executeExp(pc,sql,qr,expression.getOperand(1),row);
  try {
    return new Double(Caster.toDoubleValue(left) + Caster.toDoubleValue(right));
  }
 catch (  PageException e) {
    return Caster.toString(left) + Caster.toString(right);
  }
}

private Object executePlus ( PageContext pc , SQL sql , Query qr , ZExpression expression , int row ) throws PageException { Object left = executeExp ( pc , sql , qr , expression . getOperand ( 0 ) , row ) ; Object right = executeExp ( pc , sql , qr , expression . getOperand ( 1 ) , row ) ; try { return new Double ( Caster . toDoubleValue ( left ) + Caster . toDoubleValue ( right ) ) ; } catch ( PageException e ) { return Caster . toString ( left ) + Caster . toString ( right ) ; } }
execute a plus operation
