Re: [boost] Problem with BOOST_STATIC_ASSERT

From: David Abrahams (dave_at_[hidden])
Date: 2002-09-08 12:33:09

From: "Craig Henderson" <cdm.henderson_at_[hidden]>

> I have a problem with the BOOST_STATIC_ASSERT macros on VC++.Net. My
class

    ...

> Please could someone explain this behaviour? Am I missing something or
there
> something wrong with the macro or vc++ compatibility?

Expressions passed to BOOST_STATIC_ASSERT can only be compile-time
expressions (thus the word STATIC in the name), but typeid() is a runtime
expression. If you want a runtime assert, use <cassert>. If you want to
assert that types are the same at compile-time, try:

  #include <boost/type_traits.hpp>

  ...

    BOOST_STATIC_ASSERT((
        boost::is_same<typename Res::value_type, diff_result<T>*>::value));

or if you want equivalent behavior to your typeid() expression:

    BOOST_STATIC_ASSERT((
        boost::is_same<
            typename boost::remove_cv<
                typename boost::remove_reference<
                    typename Res::value_type
                >::type
            >::type
            , diff_result<T>*
        >::value
    ));

HTH,
Dave
-----------------------------------------------------------
           David Abrahams * Boost Consulting
dave_at_[hidden] * http://www.boost-consulting.com