Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
This is an older version of Boost and was released in 2013. The current version is 1.89.0.
ext_parser
// In header: <boost/program_options/parsers.hpp> typedef function1< std::pair< std::string, std::string >, const std::string & > ext_parser;