Chapter 1

Figure 17.10
The Start(), RunL(), and DoCancel() functions of CFlashing Hello show how to
maintain an outstanding request. Here's Start():
void CFlashingHello::Start(TTimeIntervalMicroSeconds32 aHalfPeriod)
{
_LIT(KFlashingHelloPeriodPanic, "CFlashingHello");
__ASSERT_ALWAYS(!IsActive(), User::Panic
(KFlashingHelloPeriodPanic, 1));
// Remember half-period
iHalfPeriod=aHalfPeriod;
// Hide the text, to begin with
ShowText(EFalse);
// Issue request
iTimer.After(iStatus, iHalfPeriod);
SetActive();
}
Start() begins by asserting that a request is not already active and ends by issuing a
request – just as before. Because a whole series of requests will be issued, Start()
doesn't merely pass the half-period parameter to the iTimer.After(), but stores it as a
member variable for later use.
Start()also starts off the visible aspect of the flashing process by immediately hiding the
text (which is visible until Start() is called).
When the timer completes, RunL() is called:
void CFlashingHello::RunL()
{