Function usage

lib/usage.ts:14–753

(yargs: YargsInstance, shim: PlatformShim)

}

export function usage(yargs: YargsInstance, shim: PlatformShim) {
  const __ = shim.y18n.__;
  const self = {} as UsageInstance;

  // methods for ouputting/building failure message.
  const fails: (FailureFunction | boolean)[] = [];
  self.failFn = function failFn(f) {
    fails.push(f);
  };
  let failMessage: string | nil = null;
  let globalFailMessage: string | nil = null;
  let showHelpOnFail = true;
  self.showHelpOnFail = function showHelpOnFailFn(
    arg1: boolean | string = true,
    arg2?: string
  ) {
    const [enabled, message] =
      typeof arg1 === 'string' ? [true, arg1] : [arg1, arg2];

    // If global context, set globalFailMessage
    // Addresses: https://github.com/yargs/yargs/issues/2085
    if (yargs.getInternalMethods().isGlobalContext()) {
      globalFailMessage = message;
    }

    failMessage = message;
    showHelpOnFail = enabled;
    return self;
  };

  let failureOutput = false;
  self.fail = function fail(msg, err) {
    const logger = yargs.getInternalMethods().getLoggerInstance();

    if (fails.length) {
      for (let i = fails.length - 1; i >= 0; --i) {
        const fail = fails[i];
        if (isBoolean(fail)) {
          if (err) throw err;
          else if (msg) throw Error(msg);
        } else {
          fail(msg, err, self);
        }
      }
    } else {
      if (yargs.getExitProcess()) setBlocking(true);

      // don't output failure message more than once
      if (!failureOutput) {
        failureOutput = true;
        if (showHelpOnFail) {
          yargs.showHelp('error');
          logger.error();
        }
        if (msg || err) logger.error(msg || err);
        const globalOrCommandFailMessage = failMessage || globalFailMessage;
        if (globalOrCommandFailMessage) {
          if (msg || err) logger.error('');