Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
| Front Page / Macros / Asserts / BOOST_MPL_ASSERT_NOT |
#define BOOST_MPL_ASSERT_NOT( pred ) \ unspecified token sequence \ /**/
Generates a compilation error when predicate holds true.
#include <boost/mpl/assert.hpp>
| Parameter | Requirement | Description |
|---|---|---|
| pred | Boolean nullary Metafunction | A predicate to be asserted to be false. |
For any boolean nullary Metafunction pred:
BOOST_MPL_ASSERT_NOT(( pred ));
| Return type: | None. |
|---|---|
| Semantics: | Generates a compilation error if pred::type::value != false, otherwise has no effect. Note that double parentheses are required even if no commas appear in the condition. When possible within the compiler's diagnostic capabilities, the error message will include the predicate's full type name, and have a general form of: ... ************boost::mpl::not_< pred >::************ ... |
template< typename T, typename U > struct my
{
// ...
BOOST_MPL_ASSERT_NOT(( is_same< T,U > ));
};
my<void,void> test;
// In instantiation of `my<void, void>':
// instantiated from here
// conversion from `
// mpl_::failed************boost::mpl::not_<boost::is_same<void, void>
// >::************' to non-scalar type `mpl_::assert<false>' requested