Description

The macro should be used at a namespace scope. It expands into an attribute keyword type definition, including the tag namespace and the keyword tag type within which has the following layout:

namespace tag
{
  struct keyword_ :
    public boost::log::expressions::keyword_descriptor
  {
    typedef value_type_ value_type;
    static boost::log::attribute_name get_name();
  };
}

typedef boost::log::expressions::attribute_keyword< tag::keyword_ > keyword_type;

The get_name method returns the attribute name.

	Note
	This macro only defines the type of the keyword. To also define the keyword object, use the BOOST_LOG_ATTRIBUTE_KEYWORD macro instead.