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| Commit | Line | Data |
|---|---|---|
| 7c673cae FG |
1 | .. Macros/Asserts//BOOST_MPL_ASSERT_NOT |
| 2 | ||
| 3 | BOOST_MPL_ASSERT_NOT | |
| 4 | ==================== | |
| 5 | ||
| 6 | Synopsis | |
| 7 | -------- | |
| 8 | ||
| 9 | .. parsed-literal:: | |
| 10 | ||
| 11 | #define BOOST_MPL_ASSERT_NOT( pred ) \\ | |
| 12 | |unspecified-token-seq| \\ | |
| 13 | /\*\*/ | |
| 14 | ||
| 15 | ||
| 16 | Description | |
| 17 | ----------- | |
| 18 | ||
| 19 | Generates a compilation error when predicate holds true. | |
| 20 | ||
| 21 | ||
| 22 | Header | |
| 23 | ------ | |
| 24 | ||
| 25 | .. parsed-literal:: | |
| 26 | ||
| 27 | #include <boost/mpl/assert.hpp> | |
| 28 | ||
| 29 | ||
| 30 | Parameters | |
| 31 | ---------- | |
| 32 | ||
| 33 | +---------------+-----------------------------------+-------------------------------------------+ | |
| 34 | | Parameter | Requirement | Description | | |
| 35 | +===============+===================================+===========================================+ | |
| 36 | | ``pred`` | Boolean nullary |Metafunction| | A predicate to be asserted to be false. | | |
| 37 | +---------------+-----------------------------------+-------------------------------------------+ | |
| 38 | ||
| 39 | ||
| 40 | Expression semantics | |
| 41 | -------------------- | |
| 42 | ||
| 43 | For any boolean nullary |Metafunction| ``pred``: | |
| 44 | ||
| 45 | ||
| 46 | .. parsed-literal:: | |
| 47 | ||
| 48 | BOOST_MPL_ASSERT_NOT(( pred )); | |
| 49 | ||
| 50 | :Return type: | |
| 51 | None. | |
| 52 | ||
| 53 | :Semantics: | |
| 54 | Generates a compilation error if ``pred::type::value != false``, otherwise | |
| 55 | has no effect. Note that double parentheses are required even if no commas | |
| 56 | appear in the condition. | |
| 57 | ||
| 58 | When possible within the compiler's diagnostic capabilities, | |
| 59 | the error message will include the predicate's full type name, and have a | |
| 60 | general form of: | |
| 61 | ||
| 62 | .. parsed-literal:: | |
| 63 | ||
| 64 | |...| \*\*\*\*\*\*\*\*\*\*\*\*boost::mpl::not_< pred >::\*\*\*\*\*\*\*\*\*\*\*\* |...| | |
| 65 | ||
| 66 | ||
| 67 | Example | |
| 68 | ------- | |
| 69 | ||
| 70 | :: | |
| 71 | ||
| 72 | template< typename T, typename U > struct my | |
| 73 | { | |
| 74 | // ... | |
| 75 | BOOST_MPL_ASSERT_NOT(( is_same< T,U > )); | |
| 76 | }; | |
| 77 | ||
| 78 | my<void,void> test; | |
| 79 | ||
| 80 | // In instantiation of `my<void, void>': | |
| 81 | // instantiated from here | |
| 82 | // conversion from ` | |
| 83 | // mpl_::failed************boost::mpl::not_<boost::is_same<void, void> | |
| 84 | // >::************' to non-scalar type `mpl_::assert<false>' requested | |
| 85 | ||
| 86 | ||
| 87 | See also | |
| 88 | -------- | |
| 89 | ||
| 90 | |Asserts|, |BOOST_MPL_ASSERT|, |BOOST_MPL_ASSERT_MSG|, |BOOST_MPL_ASSERT_RELATION| | |
| 91 | ||
| 92 | ||
| 93 |