[Overview][Constants][Types][Classes][Procedures and functions][Variables][Index] | Reference for unit 'Classes' (#rtl)

# IFPObserved

[Properties (by Name)] [Methods (by Name)] [Events (by Name)]

Interface implemented by an object that can be observed.

## Declaration

Source position: classesh.inc line 165

`type IFPObserved = interface`
`procedure FPOAttachObserver();` |  | Attach a new observer to the object
`procedure FPODetachObserver();` |  | Remove an observer from the list of observers.
`procedure FPONotifyObservers();` |  | Notify all observers
`end;`

## Inheritance

`IFPObserved` |  | Interface implemented by an object that can be observed.

## Description

IFPObserved is an interface which can be implemented in objects that must be observable. Objects that wish to observe the object can register themselves with the FPOAttachObserver call, and must be detached using the FPODetachObserver call.

This interface is not reference counted, so care must be taken that the ooFree message is sent with FPONotifyObservers when the object is freed.

## See also

FPONotifyObservers