Question

To access the value changes of an object over time, the notion of a Value Change (VC) traverse handle is added. A value change traverse object is used to traverse and access value changes not just for the current value (as calling vpi_get_time() or vpi_get_value() on the object handle would) but for any point in time: past, present, or future. To create a value change traverse handle the routine vpi_handle() is called with a vpiTrvsObj vpiType:

vpiHandle object_handle; /* design object */
vpiHandle trvsHndl = vpi_handle(/*vpiType*/vpiTrvsObj,
/*vpiHandle*/ object_handle);

A traverse object exists from the time it is created until its handle is released. It is the application’s responsibility to keep a handle to the created traverse object, and to release it when it is no longer needed.