onAdvise

Topic group Related topics Example

Event fired after an external application requests a DDE hot link to an item in a dBASE Plus server topic.

Parameters

<item expC>

The data item for which the external application wants to be advised when changes are made.

Property of

DDETopic

Description

Use onAdvise in a DDE server program to respond to a request for a hot link and to determine which dBASE Plus data item the link applies to. To implement a hot link in a DDETopic object, use the notify( ) method to advise all interested clients whenever the item changes.

dBASE Plus automatically maintains an internal list of all clients that asked to be notified on changes in a particular item (when the client calls their equivalent of the DDELink object’s advise( ) method). This makes onAdvise supplemental. For example, you can track those items for which there has been a notification request. Whenenver an item changes, you can call notify( ) only if someone has requested notification.

Item names are often held in tables or arrays to handle multiple hot links. For example, a client application might request a hot link to a field, passing the field name through the <item> parameter. Each time, the onAdvise event handler places the field name in an array.

The onPoke event handler would search this array each time a field is changed; if the name of the changed field is found in the array, the routine could call the notify( ) method.