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1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> |
| 2 | <html> | |
| 3 | <head> | |
| 4 | <title>Boost: assert.hpp documentation</title> | |
| 5 | <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> | |
| 6 | </head> | |
| 7 | <body bgcolor="white" style="MARGIN-LEFT: 5%; MARGIN-RIGHT: 5%"> | |
| 8 | <table border="0" width="100%"> | |
| 9 | <tr> | |
| 10 | <td width="277"><a href="../../index.htm"> <img src="../../boost.png" alt="boost.png (6897 bytes)" width="277" height="86" border="0" /></a> | |
| 11 | </td> | |
| 12 | <td align="center"> | |
| 13 | <h1>assert.hpp</h1> | |
| 14 | </td> | |
| 15 | </tr> | |
| 16 | <tr> | |
| 17 | <td colspan="2" height="64"> </td> | |
| 18 | </tr> | |
| 19 | </table> | |
| 20 | <p> | |
| 21 | <a href="#BOOST_ASSERT">BOOST_ASSERT</a><br /> | |
| 22 | <a href="#BOOST_ASSERT_MSG">BOOST_ASSERT_MSG</a><br /> | |
| 23 | <a href="#BOOST_VERIFY">BOOST_VERIFY</a><br /> | |
| 24 | <a href="#BOOST_VERIFY_MSG">BOOST_VERIFY_MSG</a><br /> | |
| 25 | <a href="#BOOST_ASSERT_IS_VOID">BOOST_ASSERT_IS_VOID</a><br /> | |
| 26 | </p> | |
| 27 | ||
| 28 | <h2><a name="BOOST_ASSERT">BOOST_ASSERT</a></h2> | |
| 29 | <p> | |
| 30 | The header <code><boost/assert.hpp></code> defines the macro <code>BOOST_ASSERT</code>, | |
| 31 | which is similar to the standard <code>assert</code> macro defined in <code><cassert></code>. | |
| 32 | The macro is intended to be used in both Boost libraries and user | |
| 33 | code. | |
| 34 | </p> | |
| 35 | <p>• By default, <code>BOOST_ASSERT(expr)</code> expands to <code>assert(expr)</code>.</p> | |
| 36 | <p>• If the macro <code>BOOST_DISABLE_ASSERTS</code> is defined when <code><boost/assert.hpp></code> | |
| 37 | is included, <code>BOOST_ASSERT(expr)</code> expands to <code>((void)0)</code>, regardless of whether | |
| 38 | the macro <code>NDEBUG</code> is defined. This allows users to selectively disable <code>BOOST_ASSERT</code> without | |
| 39 | affecting the definition of the standard <code>assert</code>.</p> | |
| 40 | <p>• If the macro <code>BOOST_ENABLE_ASSERT_HANDLER</code> is defined when <code><boost/assert.hpp></code> | |
| 41 | is included, <code>BOOST_ASSERT(expr)</code> expands to</p> | |
| 42 | <blockquote> | |
| 43 | <pre>(<a href="../config/doc/html/boost_config/boost_macro_reference.html#boost_config.boost_macro_reference.boost_helper_macros">BOOST_LIKELY</a>(!!(expr))? ((void)0): ::boost::assertion_failed(#expr, <a href="current_function.html">BOOST_CURRENT_FUNCTION</a>, __FILE__, __LINE__))</pre> | |
| 44 | </blockquote> | |
| 45 | <p>That is, it evaluates <code>expr</code> and if it's false, calls <code>::boost::assertion_failed(#expr, BOOST_CURRENT_FUNCTION, __FILE__, __LINE__)</code>. | |
| 46 | This is true regardless of whether <code>NDEBUG</code> is defined.</p> | |
| 47 | <p><code>boost::assertion_failed</code> is declared in <code><boost/assert.hpp></code> as</p> | |
| 48 | <blockquote> | |
| 49 | <pre>namespace boost | |
| 50 | { | |
| 51 | void assertion_failed(char const * expr, char const * function, char const * file, long line); | |
| 52 | } | |
| 53 | </pre> | |
| 54 | </blockquote> | |
| 55 | <p>but it is never defined. The user is expected to supply an appropriate | |
| 56 | definition.</p> | |
| 57 | <p>• If the macro <code>BOOST_ENABLE_ASSERT_DEBUG_HANDLER</code> is defined when <code><boost/assert.hpp></code> | |
| 58 | is included, <code>BOOST_ASSERT(expr)</code> expands to <code>((void)0)</code> when <code>NDEBUG</code> is | |
| 59 | defined. Otherwise the behavior is as if <code>BOOST_ENABLE_ASSERT_HANDLER</code> has been defined.</p> | |
| 60 | <p>As is the case with <code><cassert></code>, <code><boost/assert.hpp></code> | |
| 61 | can be included multiple times in a single translation unit. <code>BOOST_ASSERT</code> | |
| 62 | will be redefined each time as specified above.</p> | |
| 63 | ||
| 64 | <h2><a name="BOOST_ASSERT_MSG">BOOST_ASSERT_MSG</a></h2> | |
| 65 | <p> | |
| 66 | The macro <code>BOOST_ASSERT_MSG</code> is similar to <code>BOOST_ASSERT</code>, but it takes an additional argument, | |
| 67 | a character literal, supplying an error message.</p> | |
| 68 | <p>• By default, <code>BOOST_ASSERT_MSG(expr,msg)</code> expands to <code>assert((expr)&&(msg))</code>.</p> | |
| 69 | <p>• If the macro <code>BOOST_DISABLE_ASSERTS</code> is defined when <code><boost/assert.hpp></code> | |
| 70 | is included, <code>BOOST_ASSERT_MSG(expr,msg)</code> expands to <code>((void)0)</code>, regardless of whether | |
| 71 | the macro <code>NDEBUG</code> is defined.</p> | |
| 72 | <p>• If the macro <code>BOOST_ENABLE_ASSERT_HANDLER</code> is defined when <code><boost/assert.hpp></code> | |
| 73 | is included, <code>BOOST_ASSERT_MSG(expr,msg)</code> expands to</p> | |
| 74 | <blockquote> | |
| 75 | <pre>(<a href="../config/doc/html/boost_config/boost_macro_reference.html#boost_config.boost_macro_reference.boost_helper_macros">BOOST_LIKELY</a>(!!(expr))? ((void)0): ::boost::assertion_failed_msg(#expr, msg, <a href="current_function.html">BOOST_CURRENT_FUNCTION</a>, __FILE__, __LINE__))</pre> | |
| 76 | </blockquote> | |
| 77 | <p>This is true regardless of whether <code>NDEBUG</code> is defined.</p> | |
| 78 | <p><code>boost::assertion_failed_msg</code> is declared in <code><boost/assert.hpp></code> as</p> | |
| 79 | <blockquote> | |
| 80 | <pre>namespace boost | |
| 81 | { | |
| 82 | void assertion_failed_msg(char const * expr, char const * msg, char const * function, char const * file, long line); | |
| 83 | } | |
| 84 | </pre> | |
| 85 | </blockquote> | |
| 86 | <p>but it is never defined. The user is expected to supply an appropriate | |
| 87 | definition.</p> | |
| 88 | <p>• If the macro <code>BOOST_ENABLE_ASSERT_DEBUG_HANDLER</code> is defined when <code><boost/assert.hpp></code> | |
| 89 | is included, <code>BOOST_ASSERT_MSG(expr)</code> expands to <code>((void)0)</code> when <code>NDEBUG</code> is | |
| 90 | defined. Otherwise the behavior is as if <code>BOOST_ENABLE_ASSERT_HANDLER</code> has been defined.</p> | |
| 91 | <p>As is the case with <code><cassert></code>, <code><boost/assert.hpp></code> | |
| 92 | can be included multiple times in a single translation unit. <code>BOOST_ASSERT_MSG</code> | |
| 93 | will be redefined each time as specified above.</p> | |
| 94 | ||
| 95 | <h2><a name="BOOST_VERIFY">BOOST_VERIFY</a></h2> | |
| 96 | <p>The macro <code>BOOST_VERIFY</code> has the same behavior as <code>BOOST_ASSERT</code>, except that | |
| 97 | the expression that is passed to <code>BOOST_VERIFY</code> is always | |
| 98 | evaluated. This is useful when the asserted expression has desirable side | |
| 99 | effects; it can also help suppress warnings about unused variables when the | |
| 100 | only use of the variable is inside an assertion.</p> | |
| 101 | <p>• If the macro <code>BOOST_DISABLE_ASSERTS</code> is defined when <code><boost/assert.hpp></code> | |
| 102 | is included, <code>BOOST_VERIFY(expr)</code> expands to <code>((void)(expr))</code>.</p> | |
| 103 | <p>• If the macro <code>BOOST_ENABLE_ASSERT_HANDLER</code> is defined when <code><boost/assert.hpp></code> | |
| 104 | is included, <code>BOOST_VERIFY(expr)</code> expands to <code>BOOST_ASSERT(expr)</code>.</p> | |
| 105 | <p>• Otherwise, <code>BOOST_VERIFY(expr)</code> expands to <code>((void)(expr))</code> when <code>NDEBUG</code> is | |
| 106 | defined, to <code>BOOST_ASSERT(expr)</code> when it's not.</p> | |
| 107 | <h2><a name="BOOST_VERIFY_MSG">BOOST_VERIFY_MSG</a></h2> | |
| 108 | <p>The macro <code>BOOST_VERIFY_MSG</code> is similar to <code>BOOST_VERIFY</code>, with an additional parameter, an error message.</p> | |
| 109 | <p>• If the macro <code>BOOST_DISABLE_ASSERTS</code> is defined when <code><boost/assert.hpp></code> | |
| 110 | is included, <code>BOOST_VERIFY_MSG(expr,msg)</code> expands to <code>((void)(expr))</code>.</p> | |
| 111 | <p>• If the macro <code>BOOST_ENABLE_ASSERT_HANDLER</code> is defined when <code><boost/assert.hpp></code> | |
| 112 | is included, <code>BOOST_VERIFY_MSG(expr,msg)</code> expands to <code>BOOST_ASSERT_MSG(expr,msg)</code>.</p> | |
| 113 | <p>• Otherwise, <code>BOOST_VERIFY_MSG(expr,msg)</code> expands to <code>((void)(expr))</code> when <code>NDEBUG</code> is | |
| 114 | defined, to <code>BOOST_ASSERT_MSG(expr,msg)</code> when it's not.</p> | |
| 115 | <hr /> | |
| 116 | <p> | |
| 117 | <h2><a name="BOOST_ASSERT_IS_VOID">BOOST_ASSERT_IS_VOID</a></h2> | |
| 118 | <p>The macro <code>BOOST_ASSERT_IS_VOID</code> is defined when <code>BOOST_ASSERT</code> and <code>BOOST_ASSERT_MSG</code>, are expanded to <code>((void)0)</code>. | |
| 119 | This macro is useful to avoid compiling and potentially running code that is only intended to prepare data to be used in the assertion.</p> | |
| 120 | <blockquote> | |
| 121 | <pre> | |
| 122 | void MyContainer::erase(iterator i) | |
| 123 | { | |
| 124 | //Some sanity checks, data must be ordered | |
| 125 | #ifndef BOOST_ASSERT_IS_VOID | |
| 126 | if(i != c.begin()){ | |
| 127 | iterator prev = i; | |
| 128 | --prev; | |
| 129 | BOOST_ASSERT(*prev < *i); | |
| 130 | } | |
| 131 | else if(i != c.end()){ | |
| 132 | iterator next = i; | |
| 133 | ++next; | |
| 134 | BOOST_ASSERT(*i < *next); | |
| 135 | } | |
| 136 | #endif | |
| 137 | this->erase_impl(i); | |
| 138 | } | |
| 139 | </pre> | |
| 140 | </blockquote> | |
| 141 | ||
| 142 | ||
| 143 | <p>• By default, <code>BOOST_ASSERT_IS_VOID</code> is defined if <code>NDEBUG</code> is defined.</p> | |
| 144 | <p>• If the macro <code>BOOST_DISABLE_ASSERTS</code> is defined <code>BOOST_ASSERT_IS_VOID</code> is always defined.</p> | |
| 145 | <p>• If the macro <code>BOOST_ENABLE_ASSERT_HANDLER</code> is defined <code>BOOST_ASSERT_IS_VOID</code> is never defined.</p> | |
| 146 | <p>• If the macro <code>BOOST_ENABLE_ASSERT_DEBUG_HANDLER</code>, then <code>BOOST_ASSERT_IS_VOID</code> is defined when <code>NDEBUG</code> is defined.</p> | |
| 147 | <hr /> | |
| 148 | <p> | |
| 149 |