Question

在Boost.Log库中有一些奇怪的代码，例如在BoostFileLogging.cpp中，它说

#ifndef BOOST_LOG_DOXYGEN_PASS

#define BOOST_LOG_INIT_LOG_TO_FILE_INTERNAL(z, n, data)\
    template< BOOST_PP_ENUM_PARAMS(n, typename T) >\
    inline shared_ptr< BOOST_LOG_FILE_SINK_FRONTEND_INTERNAL< sinks::text_file_backend > > add_file_log(BOOST_PP_ENUM_BINARY_PARAMS(n, T, const& arg))\
    {\
        return aux::add_file_log((\
            aux::wrap_file_name(arg0, typename parameter::aux::is_named_argument< T0 >::type())\
            BOOST_PP_COMMA_IF(BOOST_PP_GREATER(n, 1))\
            BOOST_PP_ENUM_SHIFTED_PARAMS(n, arg)\
            ));\
    }

BOOST_PP_REPEAT_FROM_TO(1, BOOST_LOG_MAX_PARAMETER_ARGS, BOOST_LOG_INIT_LOG_TO_FILE_INTERNAL, ~)

#undef BOOST_LOG_INIT_LOG_TO_FILE_INTERNAL

#else // BOOST_LOG_DOXYGEN_PASS

/*!
 * The function initializes the logging library to write logs to a file stream.
 *
 * \param args A number of named arguments. The following parameters are supported:
 *             \li \c file_name The file name or its pattern. This parameter is mandatory.
 *             \li \c open_mode The mask that describes the open mode for the file. See <tt>std::ios_base::openmode</tt>.
 *             \li \c rotation_size The size of the file at which rotation should occur. See <tt>basic_text_file_backend</tt>.
 *             \li \c time_based_rotation The predicate for time-based file rotations. See <tt>basic_text_file_backend</tt>.
 *             \li \c auto_flush A boolean flag that shows whether the sink should automatically flush the file
 *                               after each written record.
 *             \li \c target The target directory to store rotated files in. See <tt>sinks::file::make_collector</tt>.
 *             \li \c max_size The maximum total size of rotated files in the target directory. See <tt>sinks::file::make_collector</tt>.
 *             \li \c min_free_space Minimum free space in the target directory. See <tt>sinks::file::make_collector</tt>.
 *             \li \c scan_method The method of scanning the target directory for log files. See <tt>sinks::file::scan_method</tt>.
 *             \li \c filter Specifies a filter to install into the sink. May be a string that represents a filter,
 *                           or a filter lambda expression.
 *             \li \c format Specifies a formatter to install into the sink. May be a string that represents a formatter,
 *                           or a formatter lambda expression (either streaming or Boost.Format-like notation).
 * \return Pointer to the constructed sink.
 */
template< typename... ArgsT >
shared_ptr< BOOST_LOG_FILE_SINK_FRONTEND_INTERNAL< sinks::text_file_backend > > add_file_log(ArgsT... const& args);

#endif // BOOST_LOG_DOXYGEN_PASS

这个宏的动机是什么？我应该启用它还是禁用它？它没有记录。

Answer 1

Doxygen是一个解析源代码并生成文档的程序。

这样做的目的是让Doxygen看到（和文档）与真实编译器看到的不同的东西。

在这种情况下，Doxygen会看到一个可变参数模板，因此HTML文档会说出这样的内容：

add_file_log （ArgsT ... const＆amp; args）;

模板参数：


模板＆LT; typename ... ArgsT＆gt;


返回类型：
template<typename Arg1T> shared_ptr</*snip*/> add_file_log(Arg1T const& arg1);
template<typename Arg1T, typename Arg2T> shared_ptr</*snip*/> add_file_log(Arg1T const& arg1, Arg2T const& arg2);
template<typename Arg1T, typename Arg2T, typename Arg3T> shared_ptr</*snip*/> add_file_log(Arg1T const& arg1, Arg2T const& arg2, Arg3T const& arg3);
// and so on
该函数初始化日志库以将日志写入文件流。

......等等

但Boost Log显然适用于不支持可变参数模板的编译器，因此真正的编译器无法看到这一点。编译器看到的是一堆非变量模板，这些都是这些（尽管它与解释BOOST_LOG_DOXYGEN_PASS无关）：

Intent i = new Intent(A.this, B.class);
i.putStringArrayListExtra("key", stringArrayList);
startActivity(i);

您不希望为每个文档输入单独的文档条目，这只会使文档变得混乱。

Boost.Log中的BOOST_LOG_DOXYGEN_PASS是什么？

1 个答案: