Re: runtime error when setting pointer to interface to NULL

"Alf P. Steinbach" <>
Tue, 29 Jul 2008 16:50:52 +0200
* Igor Tandetnik:

"Tim Roberts" <> wrote in message

"Igor Tandetnik" <> wrote:


Note .Release, not ->Release. It does the same as assigning NULL, but
perhaps in a more explicit and readable way.

There's more to it than that. spIClarinet->Release() bypasses the
smart pointer code in CComPtr

More to what than what? Was any part of "use .Release, not ->Release"

I also reacted to the "there's more to it".

Besides, the OP is asking about _com_ptr_t, not CComPtr. With CComPtr,
spIClarinet->Release() wouldn't even compile.

Good samaritan that I am, for Tim, the technical: CComPtr::operator-> doesn't
return a pure T*, but returns the contained pointer downcasted to a
_NoAddRefReleaseOnCComPtr<T>*, which makes AddRef and Release private.

It's still possible to access AddRef and Release in other ways, but the
(compiler-specific) trick works in practice to catch such mistakes.


- Alf

PS: I think it's much better to just provide the technical info that one has
than to invite a back-and-forth exchange about it. Providing the technical info
=> everyone improves, scientific & engineering way. Making seemingly incorrect
statement based on special case knowledge => dominance games, political way
(although in this case it might have felt justified :-), I think, still ungood).

A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

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