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Bind

Use this when your program already has destination variables and you do not want to read values back out of Args.

This page is for the case where cli20 is only one part of a larger program and the final state already lives in ordinary local variables or objects.

Source​

Source: examples/bind.cc

examples/bind.cc
// bind.cc — demonstrates BoundOption writing directly into application state.

#include <iostream>

#include "cli/argument.hh"
#include "cli/parser.hh"

struct Args {
  cli::Description description{
      "Bind parsed values into pre-existing variables instead of reading them"
      " back from Args."};
  cli::Help<> help;
  cli::BoundIntOption<"port", 'p'> port;
  cli::BoundStringOption<"output", 'o'> output;
  cli::BoundDoubleOption<"ratio"> ratio;
};

auto main(int argc, char* argv[]) -> int {
  int port = 8080;
  std::string output = "out.bin";
  double ratio = 1.0;

  Args args;
  args.port.bind(port);
  args.output.bind(output);
  args.ratio = &ratio;

  const auto result = cli::Parser<Args>{}.parse(std::move(args), argc, argv);
  if (!result) {
    std::cerr << result.error.message() << '\n';
    return result.error.exit_code();
  }

  std::cout << "port: " << port << '\n';
  std::cout << "output: " << output << '\n';
  std::cout << "ratio: " << ratio << '\n';
  return 0;
}

What This Example Shows​

This example binds parsed values directly into existing variables, so the real state lives outside Args from the start. It is useful when the surrounding program already owns port, output, and ratio, and on success those values are written straight into their target int, std::string, and double variables.

Try It​

cli20@cli20-dev: ~
cli20@cli20-dev:~$ bind

Things to try:

  • Happy path — --port 9000 --output release.bin --ratio 1.5
  • Defaults — run with no arguments to see the pre-bound default values
  • Help — --help
  • Bad ratio — --port 80 --ratio abc to see conversion fail