| .. Macros/Asserts//BOOST_MPL_ASSERT_MSG |
| |
| BOOST_MPL_ASSERT_MSG |
| ==================== |
| |
| Synopsis |
| -------- |
| |
| .. parsed-literal:: |
| |
| #define BOOST_MPL_ASSERT_MSG( condition, message, types ) \\ |
| |unspecified-token-seq| \\ |
| /\*\*/ |
| |
| |
| Description |
| ----------- |
| |
| Generates a compilation error with an embedded custom message when the condition |
| doesn't hold. |
| |
| |
| Header |
| ------ |
| |
| .. parsed-literal:: |
| |
| #include <boost/mpl/assert.hpp> |
| |
| |
| Parameters |
| ---------- |
| |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| | Parameter | Requirement | Description | |
| +===============+===================================+===============================================+ |
| | ``condition`` | An integral constant expression | A condition to be asserted. | |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| | ``message`` | A legal identifier token | A custom message in a form of a legal C++ | |
| | | | identifier token. | |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| | ``types`` | A legal function parameter list | A parenthized list of types to be displayed | |
| | | | in the error message. | |
| +---------------+-----------------------------------+-----------------------------------------------+ |
| |
| |
| Expression semantics |
| -------------------- |
| |
| For any integral constant expression ``expr``, legal C++ identifier ``message``, and |
| arbitrary types ``t1``, ``t2``,... ``tn``: |
| |
| |
| .. parsed-literal:: |
| |
| BOOST_MPL_ASSERT_MSG( expr, message, (t1, t2,... tn) ); |
| |
| :Return type: |
| None. |
| |
| :Precondition: |
| ``t1``, ``t2``,... ``tn`` are non-``void``. |
| |
| :Semantics: |
| Generates a compilation error if ``expr != true``, otherwise |
| has no effect. |
| |
| When possible within the compiler's diagnostic capabilities, |
| the error message will include the ``message`` identifier and the parenthized |
| list of ``t1``, ``t2``,... ``tn`` types, and have a general form of: |
| |
| .. parsed-literal:: |
| |
| |...| \*\*\*\*\*\*\*\*\*\*\*\*( |...|::message )\*\*\*\*\*\*\*\*\*\*\*\*)(t1, t2,... tn) |...| |
| |
| |
| .. parsed-literal:: |
| |
| BOOST_MPL_ASSERT_MSG( expr, message, (types<t1, t2,... tn>) ); |
| |
| :Return type: |
| None. |
| |
| :Precondition: |
| None. |
| |
| :Semantics: |
| Generates a compilation error if ``expr != true``, otherwise |
| has no effect. |
| |
| When possible within the compiler's diagnostics capabilities, |
| the error message will include the ``message`` identifier and the list of |
| ``t1``, ``t2``,... ``tn`` types, and have a general form of: |
| |
| .. parsed-literal:: |
| |
| |...| \*\*\*\*\*\*\*\*\*\*\*\*( |...|::message )\*\*\*\*\*\*\*\*\*\*\*\*)(types<t1, t2,... tn>) |...| |
| |
| |
| Example |
| ------- |
| |
| :: |
| |
| template< typename T > struct my |
| { |
| // ... |
| BOOST_MPL_ASSERT_MSG( |
| is_integral<T>::value |
| , NON_INTEGRAL_TYPES_ARE_NOT_ALLOWED |
| , (T) |
| ); |
| }; |
| |
| my<void*> test; |
| |
| // In instantiation of `my<void*>': |
| // instantiated from here |
| // conversion from ` |
| // mpl_::failed************(my<void*>:: |
| // NON_INTEGRAL_TYPES_ARE_NOT_ALLOWED::************)(void*) |
| // ' to non-scalar type `mpl_::assert<false>' requested |
| |
| |
| See also |
| -------- |
| |
| |Asserts|, |BOOST_MPL_ASSERT|, |BOOST_MPL_ASSERT_NOT|, |BOOST_MPL_ASSERT_RELATION| |
| |
| |
| .. 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) |