ATL bug of CComPtr?

[George2]

Hello everyone,


In the ATL Internals book, one form of constructor of CComQIPtr is implemented as this,

CComQIPtr (IUnknown* lp)
{
    p = NULL; if (lp != NULL) lp -> QueryInterface (*piid, (void**)&p);
}

I think there is a bug when QueryInterface fails, and the original value of member variable p is overwritten.

I found the in MSVC 2008, the implementation is,

atlcomcli.h

	CComQIPtr(_In_opt_ IUnknown* lp) throw()
	{
		if (lp != NULL)
			lp->QueryInterface(*piid, (void **)&p);
	}

Seems the bug is fixed? Is it a bug in old version of ATL or a bug in the book?


thanks in advance,
George