Create Command

In func, creating a command is simple. Add the Command decorator to any class:

import { Command } from 'func'

@Command({
  name: 'apple',
  alias: 'a',
})
export class MyFirstCommand {
  constructor() {
    console.log('ok')
  }
}

Create a command in file apple.ts.

Assuming your command-line tool is named hello-func, run hello-func apple or hello-func a and the terminal will display ok.

Create Option

Command-line tools often need top-level options, such as <command> --version. The Option decorator handles this elegantly:

import { Option } from 'func'

@Option({
  name: 'version',
  alias: 'v',
})
export class Version {
  constructor() {
    console.log('1.0.0')
  }
}

Create an option command in file version.ts.

After adding this class, it is triggered by --version or its alias, -v.

func lets you create aliases for any command. For a global Option, the alias uses a single -, which follows the standard CLI convention.

Create Sub-options

func also provides a SubOptions decorator for commands like <command> --<option>:

import { Command, CommandArgsProvider, SubOptions } from 'func'

@Command({
  name: 'apple',
})
@SubOptions([{ name: 'help', alias: 'h' }])
export class MyFirstSubOption {
  constructor(private arg: CommandArgsProvider) {
    if (arg.option.help) {
      console.log('HELP MESSAGE: The apple is red')
    }
  }
}

Create a command containing a sub-option in file apple.ts.

See Parameters for how to read option values.

Create Main Command

The main command is triggered when users run only the command-line tool name without parameters:

import { CommandMajor } from 'func'

@CommandMajor()
export class Main {}

If your command-line tool is named hello-func, running hello-func will trigger the main command.

Get Missing Command

In some cases, users enter parameters or commands incorrectly. Use CommandMissing to guide them with a helpful message when no Command or Option can be found:

import { CommandMissing } from 'func'

@CommandMissing()
export class Missing {
  constructor() {
    console.log('not found any commands!')
  }
}

CommandNotFound is deprecated. Use CommandMissing for new projects.