|  | 
boost::log::extract_or_throw
// In header: <boost/log/attributes/value_extraction.hpp> template<typename T, typename TagT = void> result_of::extract_or_throw< T, TagT >::type extract_or_throw(attribute_value const & value);
The function extracts an attribute value from the view. The user has to explicitly specify the type or set of possible types of the attribute value to be extracted.
| Parameters: | 
 | ||
| Returns: | The extracted value or a non-empty  | ||
| Throws: | An exception is thrown if the requested value cannot be extracted. |