| .. Macros/Asserts//BOOST_MPL_ASSERT |
| |
| BOOST_MPL_ASSERT |
| ================ |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| #define BOOST_MPL_ASSERT( pred ) \\ |
| |unspecified-token-seq| \\ |
| /\*\*/ |
| |
| |
| Description |
| ----------- |
| |
| Generates a compilation error when the predicate ``pred`` holds false. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/assert.hpp> |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-----------------------------------+-------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===================================+===============================+ |
| | ``pred`` | Boolean nullary |Metafunction| | A predicate to be asserted. | |
| +---------------+-----------------------------------+-------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| For any boolean nullary |Metafunction| ``pred``: |
| |
| |
| .. parsed-literal:: |
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| BOOST_MPL_ASSERT(( pred )); |
| |
| :Return type: |
| None. |
| |
| :Semantics: |
| Generates a compilation error if ``pred::type::value != true``, 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: |
| |
| .. parsed-literal:: |
| |
| |...| \*\*\*\*\*\*\*\*\*\*\*\* pred::\*\*\*\*\*\*\*\*\*\*\*\* |...| |
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| |
| Example |
| ------- |
| |
| :: |
| |
| template< typename T, typename U > struct my |
| { |
| // ... |
| BOOST_MPL_ASSERT(( is_same< T,U > )); |
| }; |
| |
| my<void*,char*> test; |
| |
| // In instantiation of `my<void, char*>': |
| // instantiated from here |
| // conversion from ` |
| // mpl_::failed************boost::is_same<void, char*>::************' to |
| // non-scalar type `mpl_::assert<false>' requested |
| |
| |
| See also |
| -------- |
| |
| |Asserts|, |BOOST_MPL_ASSERT_NOT|, |BOOST_MPL_ASSERT_MSG|, |BOOST_MPL_ASSERT_RELATION| |
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| .. copyright:: Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
