Whenever you or the AVM raise the ERROR condition on a constructor, the AVM raises that ERROR condition directly in the statement that instantiated the object using the NEW function, NEW statement, or DYNAMIC-NEW statement. Regardless of where in the class hierarchy the constructor is running, an ERROR raised on the constructor terminates object instantiation immediately. In addition, instead of returning an object reference to an instantiated object, the ERROR condition causes the NEW function to return no object reference, leaving any data element set to receive a value in any NEW or DYNAMIC-NEW statement unchanged.
Because ERROR raised on a constructor immediately terminates object instantiation, you cannot handle the ERROR condition on a corresponding SUPER or THIS-OBJECT statement that invokes the constructor from within another constructor. (You cannot specify NO-ERROR for either of these statements, nor can you use a CATCH block to handle errors raised on them.) You can only handle constructor errors on the statement that invokes a NEW or DYNAMIC-NEW to create the object.
Also, when a constructor raises the ERROR condition, along with terminating any further object instantiation, the AVM invokes the destructor, in reverse order of instantiation, for each super class whose constructor has already completed while instantiating the class hierarchy.
Note: Within a constructor, you can also use DELETE OBJECT THIS-OBJECT to abort class instantiation, which sets the returned object reference to the Unknown value (?). However, Progress Software Corporation recommends that you use RETURN ERROR or UNDO, THROW to return ERROR from the constructor, instead, as this both aborts class instantiation and raises an ERROR condition that you can handle in the instantiating context.
