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

# TComponent.Notification

Called by components that are freed and which received a FreeNotification.

## Declaration

Source position: classesh.inc line 1922

`protected procedure TComponent.Notification(`
`AComponent: TComponent;`
`Operation: TOperation`
`); virtual;`

## Description

Notification is called whenever a child component is destroyed, inserted or removed from the list of owned component. Components that were requested to send a notification when they are freed ((with FreeNotification) will also call Notification when they are freed.

The AComponent parameter specifies which component sends the notification, and Operation specifies whether the component is being inserted into or removed from the child component list, or whether it is being destroyed.

Descendants of TComponent can use FreeNotification to request notification of the destruction of another object. By overriding the Notification method, they can do special processing (typically, set a reference to this component to Nil) when this component is destroyed. The Notification method is called quite often in the streaming process, so speed should be a consideration when overriding this method.

## See also

TOperation |  | Operation of which a component is notified.
TComponent.FreeNotification |  | Ask the component to notify called when it is being destroyed.
TComponent.RemoveFreeNotification |  | Remove a component from the Free Notification list.

Documentation generated on: May 14 2021