BaseCommand.ts

// src/tools/BaseCommand.ts
import { Command } from 'clipanion';
import { CommandContext } from '..';

/** 
 * The BaseCommand allows us to add behind-the-scenes functionality,
 * while also allowing us to now have to add Command<CommandContext>
 * to every command manually.
*/
export abstract class BaseCommand extends Command<CommandContext> {
  abstract execute(): Promise<number | void>;
}

export default BaseCommand;

cli.ts

// src/cli.ts
import { Cli } from 'clipanion';

/** Here we setup our custom context object. */
export type CommandContext = {
  quiet: boolean;
  stdin: Readable;
  stdout: Writable;
  stderr: Writable;
};

/** Create the Clipanion instance and name it. */
const cli = new Cli<CommandContext>({
  binaryLabel: 'An example program',
  binaryName: 'toolkit',
  binaryVersion: '1.0.0',
});

/** Register our WelcomeCommand. */
cli.register(WelcomeCommand);

/** Pass in our terminal arguments. */
const command = cli.process(process.argv.slice(2));

/** Run the program. */
cli.runExit(command, {
  quiet: false,
  stdin: process.stdin,
  stdout: process.stdout,
  stderr: process.stderr,
})

WelcomeCommand.ts

// src/commands/WelcomeCommand.ts
import { BaseCommand } from '../tools/BaseCommand';
import { Command } from 'clipanion';

const message = () => `
Welcome to the Yarnberry Toolkit! The powerhouse of the ce-- the Yarnberry Cookbook!

I won't lie, the Yarnberry Toolkit uses "arcanis/Clipanion" which is new and not
overly documented so I stripped some logic from Yarn 2 😅.
`;

/** Although simple, this quickly shows what makes Clipanion unique. */
export class WelcomeCommand extends BaseCommand {
  /** We tell Clipanion to listen for `--welcome` to run this command. */
  @Command.Path('--welcome')
  /** This tells Clipanion that this is also the default command. */
  @Command.Path()
  async execute(): Promise<void> {
    /** We don't use console, instead Clipanion uses an internal context/state. */
    this.context.stdout.write(`${message().trim()}\n`);
  }
}

export default WelcomeCommand;