gistfile1.php

<?php

$io = new \Composer\IO\BufferIO();

try {
    $composer = \Composer\Factory::create($io, null, false);
} catch (\InvalidArgumentException $e) {
    if ($required) {
        $io->write($e->getMessage());
        exit(1);
    }
} catch (\Composer\Console\JsonValidationException $e) {
    $errors = ' - ' . implode(PHP_EOL . ' - ', $e->getErrors());
    $message = $e->getMessage() . ':' . PHP_EOL . $errors;
    throw new \Composer\Console\JsonValidationException($message);
}