[boost] Re: [1.32 Release] Summary of MPL changes

From: Jonathan Turkanis (technews_at_[hidden])
Date: 2004-09-03 12:41:39

"Aleksey Gurtovoy" <agurtovoy_at_[hidden]> wrote in message:

> MPL changelog for 1.32 release
> ******************************

>
> 1.  Nullary metafunction classes are no longer special-cased, and
>     are *not* identical to nullary metafunctions:
>
>     +-------------------------+---------------+---------------------------+
>     | Nullary...              | Before        | Now                       |
>     +=========================+===============+===========================+
>     | metafunction            | ``f::type``   | ``f::type``               |
>     +-------------------------+---------------+---------------------------+
>     | metafunction class      | ``c::type``   | ``c::apply<>::type`` or   |
>     |                         |               | ``c::apply::type`` [1]_   |
>     +-------------------------+---------------+---------------------------+

Great! This asymmetry has bothered me for a long time.

> 4.  ``<boost/mpl/assert_is_same.hpp>`` header has been replaced by a more
>     general ``<mpl/assert.hpp>``; the new asserts provide a significantly
>     higher-quality diagnostics. See the table below for the new equivalents of
>     the old macros:
>
>
+-------------------------------------------+-----------------------------------
------------------+
>     | Before                                    | Now
|
>
+===========================================+===================================
==================+
>     | ``BOOST_MPL_ASSERT_IS_SAME(t1, t2)``      | ``BOOST_MPL_ASSERT((
boost::is_same<t1,t2> ))``     |
>
+-------------------------------------------+-----------------------------------
------------------+
>     | ``BOOST_MPL_ASSERT_IS_NOT_SAME(t1, t2)``  | ``BOOST_MPL_ASSERT_NOT((
boost::is_same<t1,t2> ))`` |
>
+-------------------------------------------+-----------------------------------
------------------+

I liked BOOST_MPL_ASSERT_IS_SAME because I didn't have to use double
parantheses. For the other uses now supported by BOOST_MPL_ASSERT, I could just
use BOOST_STATIC_ASSERT.

BTW, I remember that the reference documentation on boost consulting (or
somewhere) used to include documentation of some important macros. Why not add
this to the main docs?

Best Regards,
Jonathan