Destructor. Frees all resources owned by the object, prior to its destruction.

In particular, it cancels any outstanding request to the Kernel side change notifier before closing the handle to it.

Returns the last set of change events.

If the last outstanding request completed normally, the function returns a bit pattern where each bit value corresponds to one of the enumerators defined by TChanges. A set bit indicates that the corresponding change event occurred.

For example, if the bit value TChanges::EChangesMidnightCrossover is set, then the system time has passed midnight.

TChanges

Implements cancellation of an outstanding request.

This function is called as part of the active object's Cancel() .

It must call the appropriate cancel function offered by the active object's asynchronous service provider. The asynchronous service provider's cancel is expected to act immediately.

DoCancel() must not wait for event completion; this is handled by Cancel() .

CActive::Cancel

Constructs a new environment change notifier object with the specified active object priority and callback function.

The function requires a priority value for this active object and a reference to a TCallBack object encapsulating a pointer to the call back function which is to run when change events occur.

As part of its implementation, the function:

creates a Kernel side change notifier and opens a handle (an RChangeNotifier ) to it.

adds this active object to the current active scheduler.

Note that construction of the environment change notifier does not issue any requests for change events.

CEnvironmentChangeNotifier::Start() CActive::TPriority

Handles an active object's request completion event.

A derived class must provide an implementation to handle the completed request. If appropriate, it may issue another request.

The function is called by the active scheduler when a request completion event occurs, i.e. after the active scheduler's WaitForAnyRequest() function completes.

Before calling this active object's RunL() function, the active scheduler has:

1. decided that this is the highest priority active object with a completed request

2. marked this active object's request as complete (i.e. the request is no longer outstanding)

RunL() runs under a trap harness in the active scheduler. If it leaves, then the active scheduler calls RunError() to handle the leave.

Note that once the active scheduler's Start() function has been called, all user code is run under one of the program's active object's RunL() or RunError() functions.

CActiveScheduler::Start CActiveScheduler::Error CActiveScheduler::WaitForAnyRequest TRAPD

Sets the callback function.

A callback is normally set when this active object is constructed through the NewL() function. This function replaces any existing callback object with the specified callback object.

Issues a request for change events.

The request completes when change events occur, as signalled by the Kernel side change notifier service. The request may also complete if it is cancelled by calling the Cancel() member function of this active object.

When change events occur, the callback function is called.

Note that after the first call to this function, the callback function is called immediately; this is because of the way the underlying change notifier is implemented. The changes reported are all those defined by the TChanges enum.

CActive::Cancel() TChanges