Re: [boost] [system][chrono] header-only libs

Subject: Re: [boost] [system][chrono] header-only libs
From: Anthony Williams (anthony.ajw_at_[hidden])
Date: 2010-10-14 02:53:37

"vicente.botet" <vicente.botet_at_[hidden]> writes:

> I understand that you should have found some issues including
> <windows.h> file. I see that other libraries as FileSystem,
> Flyweithts, Interprocess, interlocked ... include it as you said:
>
> #if defined(BOOST_USE_WINDOWS_H)
> #  include <windows.h>
> #else
> // extern declaration
> #endif
>
> Unfortunately not all files including <windows.h> are protected in
> this way. Is BOOST_USE_WINDOWS_H the offical macro to use? is this
> described somewhere?

It isn't documented anywhere that I can see, but it is used by lots of
libraries.

> As there are quite a lot of files that includes some parts of
> <windows.h> some of them include the same declarations. I was
> wondering if we can not add a boost/detail/windows.hpp> file that will
> declare whatever is needed in Boost. Is this a good or a bad idea?

I think that's a bad idea, as lots of libraries will need to touch it,
and it will end up getting big and bloated like <windows.h>. A
boost/details/windows directory with a lot of special-purpose files
would be better.

> As other platforms include other macros, shouldn't I do the same for
> this files?

You mean <pthread.h> defines macros, so should we protect against that
in the same way (for example)?

If the header is as all-encompassing and messy as <windows.h> then
yes. However, there are not many platforms where just about everything
is a macro (e.g. because there are xxxA and xxxW versions of each function
that takes a string), and there are macros that actively trample on
common identifiers such as min and max (this even makes using std::min
and std::max from <algorithm> tricky --- I end up using std::min<>
everywhere to avoid being bitten).

Anthony
-- 
Author of C++ Concurrency in Action     http://www.stdthread.co.uk/book/
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