. NET 2.0 event mechanism simplifies...

 

Case:The ASPX page has a control. You want to click the control button to perform some operations to obtain a datatable and bind the datatable to the Data Control on the page.

Control CS file:

1. Define proxy

Public   Delegate   Void Retrievetargetshandler ( Object Sender, retrieveeventargs E );

Public ClassRetrieveeventargs: eventargs
{
PrivateDatatable resulttable;

PublicDatatable resulttable
{
Get{ReturnResulttable ;}
}

PublicRetrieveeventargs (datatable RET)
:Base()
{
This. Resulttable=RET;
}
}

2. Define events

Public   Event Retrievetargetshandler retrievetargets;

3. When you click the control button,

Protected   Void Btnsearchbyconditions_click ( Object Sender, eventargs E)
{
Datatable dt =   New Datatable ();
//
Retrievetargets ( This , New Retrieveeventargs (DT ));
}

In page_load of the aspx page,Instantiate the proxy and specify the processing method.

This . Targetsearchbyconditions1.retrievetargets + =   New Retrievetargetshandler (targetsearchbyconditions1_retrievetargets );

VoidTargetsearchbyconditions1_retrievetargets (ObjectSender, retrieveeventargs E)
{
Datatable dt=E. resulttable;
Response. Write ("Yes. Good!");
}

In. net1.1,

If you want your class to triggerEventnameEvent, you need the following elements.

• the class that holds event data, named eventname eventargs. This class must be exported from system. eventargs.
• event Delegate, named eventname eventhandler.
• the class that triggers the event. This class must provide:
  1. event declaration.

       [C #]  public event  eventname  eventhandler  eventname ;  [Visual Basic]  public event eventname as eventnameeventhandler 

  2. Method for triggering the event, named on eventname .