Method AutomationObject():dynamicCast() Foundation

The class AutomationObject is the generic base class for all automation and ActiveX objects. Instances of the AutomationObject class are used to connect to a COM/ActiveX component in order to access its methods and properties. Likewise, of a COM object is returned as the result of a method call, it is returned as an object of the AutomationObject class.

When working with COM/ActiveX components, an application often uses subclasses of the AutomationObject class to communicate with the COM/ActiveX component. If the application needs to respond to COM events, for example, an object of class ActiveXObject is required. Likewise, writing wrapper classes for COM/ActiveX objects often involves exposing specialized methods or instance variables. This introduces the requirement to cast an AutomationObject to an instance of another automation class. For this, the method :dynamicCast() can be used.

The method :dynamicCast() creates an instance of the class passed in parameter <xClass> and connects it to the COM/ActiveX object.

// 
// Example for using :dynamicCast() to react to an 
// event exposed by a COM object created via :CreateObject() 
// 
#PRAGMA LIBRARY("ASCOM10.LIB") 

PROCEDURE Main() 

 LOCAL oObj 

   // Cast an AutomationObject to an instance of the ActiveXObject class 
   oObj := CreateObject( "Word.Application" ) 
   oObj := oObj:dynamicCast( ActiveXObject() ) 
   oObj:visible := .T. 

   oObj:quit := {|| MsgBox("Word Application has closed!")} 

   WAIT 
RETURN