Re: [boost] C++0x and Boost

From: AlisdairM (alisdair.meredith_at_[hidden])
Date: 2006-11-22 20:41:44

Douglas Gregor wrote:

> To support this goal, I have committed a set of changes to the Boost
> config library (on CVS HEAD), which add several new macros to indicate
> the availability of C++0x features. The list involves only features
> that I know have been implemented; see below for the compilers that
> support various features. The new configuration macros are:
> 
>   BOOST_CXX0X_LONG_LONG: long long support (aliases
> BOOST_HAS_LONG_LONG)   BOOST_CXX0X_PREPROCESSOR: C99 preprocessor
> extensions   BOOST_CXX0X_RVALUE_REFERENCES: rvalue references
>   BOOST_CXX0X_STATIC_ASSERT: static assertions
>   BOOST_CXX0X_CONCEPTS: concepts (not yet accepted)
>   BOOST_CXX0X_VARIADIC_TEMPLATES: variadic templates (not yet
> accepted)

Should these be positive or negative feature tests?
I am imagining that once tests for these features are in place, library
maintainers will not want to revisit code once C++0x is published to
test for BOOST_NO_VARIADIC_TEMPLATES instead.  The latter form is more
typical of how we deal with feature-detection today.

As library maintainer John Maddoc should get the final call, but my
preference would be BOOST_NO_FEATURE forms.  It should be fairly easy
to create a single header that all compiler configs can use, and then
selectively undef features in the compiler config file itself as new
features are implemented.

> This list will grow as more C++0x features become available in
> compilers. 

Other features I am aware of:
  I believe MSVC implements delegating constructors, although that may
be only in C++/CLI mode.  Likewise, I am not sure about nullptr.

I believe Borland implement C99 preprocessor extensions in their C++
compiler.  Suspect several others do too.

and of course, most compilers implement long long now.

-- 
AlisdairM