[Insight-developers] Empty FixedArray destructor: Performancehit using gcc (times 2)

[Niels Dekker]

Bill Lorensen wrote:
> Here is an FAQ on destructors:
> http://www.informit.com/guides/content.aspx?g=cplusplus&seqNum=370
> They say that an empty destructor is pretty much useless.

The destructor of FixedArray<TValueType, VLength> invokes the destructor 
of TValueType for all of its elements.  So it may not be as empty as it 
seems...  When the destructor is removed from FixedArray, it will be 
implicitly defined as an inline function, as the FAQ you're referring to 
says.  This might give a performance gain, but it might also produce a 
larger binary.  Things might get worse (or better?) when TValueType 
itself has also has an inline destructor.

In some special cases, the destructor of a class /must/ be implemented 
in a CXX file, even if it is empty. As is the case discussed at 
GameDev.Net, "auto_ptr within Pimpl Class", 
http://www.gamedev.net/community/forums/topic.asp?topic_id=437587

Anyway, just my 2 cents.  It might still be okay to remove FixedArray's 
destructor...

Kind regards,
--
Niels Dekker
http://www.xs4all.nl/~nd/dekkerware
Scientific programmer at LKEB, Leiden University Medical Center