add example for .bind

examples/5 bind.cxx

@@ -0,0 +1,53 @@
+#include <ProgramOptions.hxx>
+#include <cstdint>
+#include <vector>
+#include <string>
+#include <iostream>
+#include <string_view>
+
+int main( int argc, char** argv ) {
+ po::parser parser;
+
+ std::uint32_t optimization = 0; // the value we set here acts as an implicit fallback
+ parser[ "optimization" ] // corresponds to --optimization
+ .abbreviation( 'O' ) // corresponds to -O
+ .description( "set the optimization level (default: -O0)" )
+ .bind( optimization ); // write the parsed value to the variable 'optimization'
+ // .bind( optimization ) automatically calls .type( po::u32 ) and .single()
+
+ std::vector< std::string > include_paths;
+ parser[ "include-path" ] // corresponds to --include-path
+ .abbreviation( 'I' ) // corresponds to -I
+ .description( "add an include path" )
+ .bind( include_paths ); // append paths to the vector 'include_paths'
+
+ parser[ "help" ] // corresponds to --help
+ .abbreviation( '?' ) // corresponds to -?
+ .description( "print this help screen" );
+
+ std::deque< std::string > files;
+ parser[ "" ] // the unnamed parameter is used for non-option arguments, i.e. gcc a.c b.c
+ .bind( files ); // append paths to the deque 'include_paths
+
+ // parsing returns false if at least one error has occurred
+ if( !parser( argc, argv ) )
+ return -1;
+
+ // we don't want to print anything else if the help screen has been displayed
+ if( parser[ "help" ].was_set() ) {
+ std::cout << parser << '\n';
+ return 0;
+ }
+
+ // print the parsed values
+ // note that we don't need to access parser anymore; all data is stored in the bound variables
+ std::cout << "optimization level = " << optimization << '\n';
+
+ std::cout << "include files (" << files.size() << "):\n";
+ for( auto&& i : files )
+ std::cout << '\t' << i << '\n';
+
+ std::cout << "include paths (" << include_paths.size() << "):\n";
+ for( auto&& i : include_paths )
+ std::cout << '\t' << i << '\n';
+}