Re: External header guards

Nikolai Pretzell wrote:
> Jens-Heiner Rechtien schrieb:
>  > Jan Holesovsky wrote:
>  >> On Monday 18 December 2006 11:46, Thorsten Behrens wrote:
>  > Kai Backman wrote:
>  >>>> Aah. Let me rephrase. Are -you- really sure the external include 
> guard
>  >>>> optimization provides enough benefit on all the compilers we are 
> using
>  >>>> to make it worthwhile to degrade readability by adding noise?
>
>  >>> ok, seems we've deadlocked here. ;-)
>
>  >>> Point is, the vast majority of the code uses that idiom as of today,
>  >>> and I'm reluctant to advice people of the contrary
>  >>> [...]
>  >>> - if people think it's ok to start removing external
>  >>> header guards right now (because it will take years to clean them up
>  >>> anyway), I'd be fine with that, too.
>  >>
>  >> I hate them that much that I am willing to do a script that would do
>  >> the removal ;-)
>  >>
>  >> What is the platform/compiler that probably needs this, please?  Any
>  >> volunteer to do a comparison of the "with" and "without" compilation
>  >> times?
>  >
>  > The one remaining compiler is Microsoft Visual
>  > Studio. There are varying reports if this compiler has a build-in
>  > "include guard optimization" or not.
>
> According to Oliver Bolte, in version 8, the MSVC compiler uses the 
> trick to connect a define (of an internal include guard) with the 
> correlating header, which is one possble way to implement this, but v.7 
> does not.
>
>
> Anyway, I would go with Thorstens remark: We will need years to remove 
> the existing external include guards anyway. IMHO there is no 
> significant performance gain by adding more of them now.
>
> So my
> Suggestion
> ----------
> is: From today on, we use internal include guards only.
> Until this has a measurable effect on our build times, we will use a 
> newer version of MSVC.
>
> What do you think?

i would appreciate this decision as well and would change the cppumaker 
accordingly if we will do it this way in the future.

Maybe someone has time to create a clever script to remove the external 
guards via script in minutes ;-)

Juergen

> Nikolai
>
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