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From: David Abrahams (david.abrahams_at_[hidden])
Date: 2001-07-03 11:50:06

----- Original Message -----
From: "Jeff Paquette" <paquette_at_[hidden]>

> Include guards can and are also used to prevent the header from being
> reparsed (as suggested by Lakos). As such, it (IMHO) would be better if
> guard referenced the file name.
> I'd rather write:
> #if !defined(BOOST_XXX)
> #include "boost/xxx"
> #endif
> than
> #if !defined("68C2D2A0-6FD1-11d5-8F0C-00105AC8B6E1")
> #include "boost/xxx"
> #endif

This practice is unreliable with most headers. For example, you can't do
that with your system headers if you're writing portable code. Most standard
and 3rd party libraries don't document their #include guard conventions, so
you have to look inside the header to determine what guard they used -- and
there's no guarantee they won't change it.

We could of course establish such a convention with boost headers, but I am
unconvinced of the benefits.

Finally, many modern compilers have learned to recognize #include guards
such that this functionality is automated and you get zero benefit from
cluttering files with such checks.


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