## Struct template basic_formatted_sink_backend

boost::log::sinks::basic_formatted_sink_backend — A base class for a logging sink backend with message formatting support.

## Synopsis

    // In header: <boost/log/sinks/basic_sink_backend.hpp>

    template<typename CharT,
             typename FrontendRequirementsT = synchronized_feeding>
    struct basic_formatted_sink_backend : public basic_sink_backend< combine_requirements< FrontendRequirementsT, formatted_records >::type >
    {
      // types
      typedef CharT                            char_type;              // Character type.
      typedef std::basic_string< char_type >   string_type;            // Formatted string type.
      typedef base_type::frontend_requirements frontend_requirements;  // Frontend requirements.
    };

## Description

The `basic_formatted_sink_backend` class template indicates to the frontend that the backend requires logging record formatting.

The class allows to request encoding conversion in case if the sink backend requires the formatted string in some particular encoding (e.g. if underlying API supports only narrow or wide characters). In order to perform conversion one should specify the desired final character type in the `TargetCharT` template parameter.