Add usage examples, some description, some reference

example/string_to_enum.cpp

@@ -0,0 +1,55 @@
+#include <boost/describe.hpp>
+#include <boost/mp11.hpp>
+#include <stdexcept>
+#include <typeinfo>
+#include <cstring>
+
+[[noreturn]] void throw_invalid_name( char const * name, char const * type )
+{
+    throw std::runtime_error(
+        std::string( "Invalid enumerator name '" ) + name + "' for enum type '" + type + "'" );
+}
+
+template<class E> E string_to_enum( char const * name )
+{
+    bool found = false;
+    E r = {};
+
+    boost::mp11::mp_for_each< boost::describe::describe_enumerators<E> >([&](auto D){
+
+        if( !found && std::strcmp( D.name, name ) == 0 )
+        {
+            found = true;
+            r = D.value;
+        }
+
+    });
+
+    if( found )
+    {
+        return r;
+    }
+    else
+    {
+        throw_invalid_name( name, typeid( E ).name() );
+    }
+}
+
+#include <iostream>
+
+BOOST_DEFINE_ENUM(E, v1, v2, v3)
+
+int main()
+{
+    try
+    {
+        std::cout << "v1: " << string_to_enum<E>( "v1" ) << std::endl;
+        std::cout << "v2: " << string_to_enum<E>( "v2" ) << std::endl;
+        std::cout << "v3: " << string_to_enum<E>( "v3" ) << std::endl;
+        std::cout << "v4: " << string_to_enum<E>( "v4" ) << std::endl;
+    }
+    catch( std::exception const & x )
+    {
+        std::cout << x.what() << std::endl;
+    }
+}