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编译用于创建boost.log格式的代码时出错

boost-logging boost-log boost c++

0

ivan.ukr · 技术社区 · 6 年前

我试图在Gbunc7.3.0上编译以下代码,其中Ubuntu 18.04 LTS具有选项-STD= C++ 14:

auto createLogFormatter()
{
    boost::log::expressions::stream_type stream;
    stream  << boost::log::expressions::format_date_time<boost::posix_time::ptime>("TimeStamp", "%Y-%m-%d %H:%M:%S  ")
            << boost::log::expressions::attr<int>("Severity")
            << " " // ERROR HERE
            << boost::log::expressions::attr<boost::log::attributes::current_thread_id::value_type>("ThreadID")
            << " "
            << boost::log::expressions::smessage;
    return stream;
}

出现奇怪的错误:

Log.cpp:51:13: error: no match for âoperator<<â (operand types are âboost::log::v2_mt_posix::expressions::aux::make_output_actor<boost::phoenix::actor<boost::log::v2_mt_posix::expressions::aux::attribute_output_terminal<boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::argument<2> >, 0> >, boost::posix_time::ptime, boost::log::v2_mt_posix::fallback_to_none, boost::log::v2_mt_posix::aux::light_function<void(boost::log::v2_mt_posix::basic_formatting_ostream<char>&, const boost::posix_time::ptime&)> > >, boost::log::v2_mt_posix::expressions::attribute_actor<int, boost::log::v2_mt_posix::fallback_to_none, void, boost::phoenix::actor>, int, false>::type {aka boost::phoenix::actor<boost::log::v2_mt_posix::expressions::aux::attribute_output_terminal<boost::phoenix::actor<boost::log::v2_mt_posix::expressions::aux::attribute_output_terminal<boost::phoenix::actor<boost::proto::exprns_::basic_expr<boost::proto::tagns_::tag::terminal, boost::proto::argsns_::term<boost::phoenix::argument<2> >, 0> >, boost::posix_time::ptime, boost::log::v2_mt_posix::fallback_to_none, boost::log::v2_mt_posix::aux::light_function<void(boost::log::v2_mt_posix::basic_formatting_ostream<char>&, const boost::posix_time::ptime&)> > >, int, boost::log::v2_mt_posix::fallback_to_none, boost::log::v2_mt_posix::to_log_fun<void> > >}â and âconst char [2]â)
     stream  << boost::log::expressions::format_date_time<boost::posix_time::ptime>("TimeStamp", "%Y-%m-%d %H:%M:%S  ")
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
             << boost::log::expressions::attr<int>("Severity")
             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
             << " "
             ^~~~~~

根据Boost示例 here ,这样做应该有效:

    expr::stream
        << expr::attr< unsigned int >("LineID")
        << ": <" << logging::trivial::severity
        << "> " << expr::smessage

但我得到了这样的错误。我做错了什么?

1 回复 | 直到 5 年前

1

Andrey Semashev 5 年前

编译器错误可能是由缺少的include引起的。lambda表达式运算符由boost.phoenix in提供 boost/phoenix/operator.hpp . 或者你可以包括 boost/log/expressions.hpp 提供所有boost.log表达式节点和运算符。

但除此之外,你的 createLogFormatter 函数不正确,因为它丢弃了整个格式化程序表达式。您不应该创建并返回 stream 对象,它只是一个启动格式化程序表达式的终端。您需要返回作为lambda表达式的结果创建的函数对象。

auto createLogFormatter()
{
    auto fmt = stream  << boost::log::expressions::format_date_time<boost::posix_time::ptime>("TimeStamp", "%Y-%m-%d %H:%M:%S  ")
            << boost::log::expressions::attr<int>("Severity")
            << " " // ERROR HERE
            << boost::log::expressions::attr<boost::log::attributes::current_thread_id::value_type>("ThreadID")
            << " "
            << boost::log::expressions::smessage;
    return fmt;
}

如果要有稳定的返回类型,可以使用 boost::log::formatter 包装表达式。