Re: simple nsIWebProgressListener question

> However, why not just use:
> NS_IMPL_ISUPPORTS4(nsSampleImpl, nsIWebProgressListener,
> nsISupportsWeakReference, nsIObserver, nsISample)
> 
> (if you do that, you have to remove NS_IMPL_ADDREF and NS_IMPL_RELEASE)
> 
> 
> --
Hi Christian,

Thanks for your quick response.

After implementing NS_IMPL_ISUPPORTS4(nsSampleImpl,
nsIWebProgressListener,
 nsISupportsWeakReference, nsIObserver, nsISample), things seem to be
better.

However, now, my program crashed at the macro
NS_GENERIC_FACTORY_CONSTRUCTOR(nsSampleImpl) ==
nsSampleImplConstructor().  nsSampleImplConstructor() functionis is
listed under nsModule ComponentInfo components[].  The exact point
that crashed inside nsSampleImplConstructor() is inst->AddRef().

inst seems to carry invalid information:

-	inst	0x009dbe90
+	nsIWebProgressListener	{...}
-	nsSupportsWeakReference	{...}
-	nsISupportsWeakReference	{...}
-	nsISupports	{...}
-	__vfptr	0xfeeefeee
	[0]	CXX0030: Error: expression cannot be evaluated
	[1]	CXX0030: Error: expression cannot be evaluated
	[2]	CXX0030: Error: expression cannot be evaluated
+	mProxy	0xfeeefeee
+	nsIObserver	{...}
-	nsISample	{...}
-	nsISupports	{...}
-	__vfptr	0xfeeefeee
	[0]	CXX0030: Error: expression cannot be evaluated
	[1]	CXX0030: Error: expression cannot be evaluated
	[2]	CXX0030: Error: expression cannot be evaluated
+	mRefCnt	{...}
+	_mOwningThread	{...}
+	mValue	0xfeeefeee ""

The callstack is as follows:

nsSampleImplConstructor() line 99
nsGenericFactory::CreateInstance() line 82 + 21 bytes
nsComponentManagerImpl::CreateInstanceByContractID() line 2000 + 24
bytes
nsComponentManagerImpl::GetServiceByContractID() line 2420 + 50 bytes
nsGetServiceByContractID::operator()() line 121 + 38 bytes
nsCOMPtr_base::assign_from_helper() line 114 + 18 bytes
nsCOMPtr<nsISupports>::nsCOMPtr<nsISupports>() line 846
NS_CreateServicesFromCategory() line 785 + 37 bytes
NS_InitXPCOM2() line 633 + 17 bytes
NS_InitXPCOM2() line 173 + 18 bytes
GRE_Startup() line 477 + 35 bytes
main() line 1705 + 5 bytes
mainCRTStartup() line 338 + 17 bytes
KERNEL32! 77e814c7()

I realised that nsSampleImpl and ~nsSampleImpl are called once before
the crashed occurs:

nsSampleImpl() enter.
~nsSampleImpl() enter
~nsSampleImpl() exit.
nsSampleImpl() exit.
-------------------
crashed occurs
-------------------

I am wonder if you know what's went wrong, please help me if you got
any idea.

Thanks,
YueWeng