EvtHandler::SendDown

Section: ET++ method description (n)
Updated: automatically Fri Mar 15 14:09:27 1991
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NAME

EvtHandler::SendDown - instance method

TEMPLATE

void SendDown(int id, int part, void * value)

SPECIFIERS

public virtual

DESCRIPTION

SendDown sends a request down the VObject tree. Similar to the method Control and the method Send, SendDown also provides a kind of communication mechanism. Control and Send send an event to the next handler, respectively to the observers. SendDown has the same arguments but instead of events they describe requests or queries to be answered by one or several VObjects of the VObject tree starting at this. By means of SendDown a VObject up in the hierarchy can request other objects down in the tree to do certain things or return some data.
For example, the method OneOfCluster::SetItemOn uses SendDown to switch one of the contained buttons on and all others off. The buttons are usually OnOffItems (see method OnOffItem::SendDown). Another example is the method Dialog::Control which uses SendDown to "validate" all EditTextItems in the dialog tree (see method EditTextItem::SendDown).
SendDown should be overridden and forwarded if a VObject has one or several inner VObjects (e.g. the method CompositeVObject::SendDown). Method is sometimes overridden.

ARGUMENTS

int id: the id of an object or of a certain request
int part: a code that describes the request more detailed
void * value: an optional argument whose exact type must be determined by the values of id and part

RETURN ARGUMENT

void

FIRST DEFINITION

class EvtHandler

FILES

implementation:: EvtHandler.C

KNOWN PROBLEMS

Why isn't SendDown first defined in the class VObject ?

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Time: 00:40:27 GMT, March 30, 2022