@black-flag/core
v3.0.3
A declarative framework for building fluent, deeply hierarchical command line interfaces with yargs
19/weekUpdated 7 months agoMITUnpacked: 174.3 KB
Published by Xunnamius
npm install @black-flag/core
A declarative wrapper around Yargs for building beautiful, fluent command line interfaces
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Black Flag 🏴
Black Flag is a fairly thin library that wraps [yargs][1], extending its
capabilities with several powerful declarative features. It can be used to
create simple single-level CLIs or deeply nested sprawling interfaces alike.
Black Flag was built as a drop-in replacement for vanilla Yargs, specifically
for users of the [yargs::commandDir()][2] ([which][3] [has][4] [its][5]
[issues][6]). Its features include:
- [Declarative-first sync/async APIs][7] ✨
- [Zero configuration required][8] ✨
- [It's still yargs all the way down][9] ✨ (nothing brand new to learn!)
- [Built-in support for dynamic options][10] ✨ ([an][11] [infamous][12]
[Yargs][13] [white][14] [whale][15])
- [Consistent and safe CLI execution][16] ✨
- [Simple comprehensive error handling][17] ✨
- [A pleasant testing experience][18] ✨
- [Builtin TypeScript intellisense][19] ✨
Black Flag is tested on Ubuntu and Windows 10, and like Yargs tracks Node.js LTS
versions. Also comes with first-class support for both CJS and ESM source.
❖ [Quick start][20]\
❖ [Step-by-step getting started guide][21]\
❖ [Black Flag versus vanilla Yargs][22]\
❖ [Simple demo CLI project][23] (or npx -p @black-flag/demo myctl --help)\
❖ [Black Flag recipes for solving common CLI design problems][24]\
❖ [Black Flag's intro examples][25] (which are just [Yargs's intro examples][26] rewritten with Black Flag)
❖ [Builder API][27] (essentially yargs::options's opt keys)\
❖ [Command module API][28]\
❖ [Configuration hooks API][29]\
❖ [BFE extended builder API][30]\
❖ [All @black-flag/core exports][31]\
❖ [All @black-flag/core/util exports][32]\
❖ [All @black-flag/extensions exports][33]\
❖ [All @black-flag/checks exports][34]
> [!TIP]
>
> If you find yourself a fan of Black Flag's more declarative DX and want to go
> all the way, check out [Black Flag Extensions][35] (BFE). BFE is a collection
> of surprisingly simple set-theoretic APIs that build on
> [yargs::options()][27] for a fully declarative developer experience. BFE
> also protects you from [a couple Yargs footguns][36] that Black Flag by itself
> cannot.
>
> You may also be interested in [Black Flag Checks][37] (BFC), which offers
> several pluggable [yargs::check][38] functions—like checkIsNotNegative and
> checkArrayNotEmpty—built to work with BFE.
---
- Install
- Quick Start
- Appendix 🏴
- Terminology
- Inspiration
- Published Package Details
- License
- Contributing and Support
- Contributors
Install
To install:
``shell`
npm install @black-flag/core
And if you're ready to go all in on Black Flag's declarative API, check out
[Black Flag Extensions][35]:
`shell`
npm install @black-flag/extensions
Quick Start
Install Black Flag:
`shell`
npm install @black-flag/core
Create the file that will run your CLI, perhaps at ./cli.js:
> [!TIP]
>
> Both CJS and ESM source is acceptable!
`js
#!/usr/bin/env node
import { runProgram } from '@black-flag/core';
export default runProgram(import.meta.resolve('./commands'));
`
Then create the root command, perhaps at ./commands/index.js:
`js`
export const name = 'pirate-parser';
export const usage = 'Usage: $0
Finally, create a subcommand, perhaps at ./commands/hello.js:
`js
export const command = '$0 [name]';
export const description =
'Welcome ter black flag, a declarative wrapper around yargs!';
export function builder(blackFlag, helpOrVersionSet, argv) {
blackFlag.positional('name', {
type: 'string',
default: 'Cambi',
describe: 'The name to say hello to'
});
// A special --attention flag only available when greeting the captain!
if (helpOrVersionSet || argv?.name === 'CAPTAIN') {
return {
attention: {
boolean: true,
description: Alert the watch${
helpOrVersionSet ? ' (only available when greeting captain)' : ''
}
}
};
}
}
export async function handler(argv) {
if (argv.attention) {
console.log('-!- Captain is on the bridge -!-');
}
console.log(Hello ${argv.name}, welcome to Black Flag!);`
}
> [!TIP]
>
> This example demonstrates a multi-level or "nested" command, i.e. a _root
> command_ with a _subcommand_. If instead we wanted to make a simple
> single-level CLI with no subcommands at all, we could merge
> ./commands/hello.js's exports (handler, builder, etc) into./commands/index.js
> .
>
> How you design your CLI is up to you!
Then run it:
`shell`
node cli.js --help
`text
Usage: pirate-parser
Commands:
pirate-parser hello Welcome ter black flag, a declarative wrapper around yargs!
Options:
--help Show help text [boolean]
--version Show version number [boolean]
`
---
`shell`
node cli.js hello --help
`text
Usage: pirate-parser hello [name]
Welcome ter black flag, a declarative wrapper around yargs!
Positionals:
name The name to say hello to [string] [default: "Cambi"]
Options:
--help Show help text [boolean]
--attention Alert the watch (only available when greeting captain) [boolean]
`
---
`shell`
node cli.js hello Parrot
`text`
Hello Parrot, welcome to Black Flag!
---
`shell`
node cli.js hello CAPTAIN
`text`
Hello CAPTAIN, welcome to Black Flag!
---
`shell`
node cli.js hello Parrot --attention
`text
Usage: pirate-parser hello [name]
Positionals:
name The name to say hello to [string] [default: "Cambi"]
Options:
--help Show help text [boolean]
Unknown argument: attention
`
---
`shell`
node cli.js hello CAPTAIN --attention
`text`
-!- Captain is on the bridge -!-
Hello CAPTAIN, welcome to Black Flag!
> [!TIP]
>
> Not sure what makes Black Flag "more declarative" than Yargs? Compare this
> quick start example to the
> vanilla Yargs version.
Next steps:
- [Check out the step-by-step getting started guide][21]
- [Compare Black Flag versus vanilla Yargs][22]
- [Play with a simple demo CLI project][23] (or
npx -p @black-flag/demo myctl --help)
- [Review Black Flag recipes for solving common CLI design problems][24]
- [Deep dive into Black Flag's internals][39]
- [Pull up Black Flag's introductory examples][25] (or [Yargs's][26])
- [Pore over Yargs's parser tricks][40] (which also apply to Black Flag)
Appendix 🏴
Further documentation can be found under [docs/][x-repo-docs] anddocs/api/
[][41]. Common CLI design "recipes" can be found underexamples/
[][24].
$3
| Term | Description |
| :-------------: | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| command | A "command" is a functional unit associated with a [configuration][28] file and represented internally as a trio of programs: [effector, helper, and router][39]. Further, each command is classified as one of: "pure parent" (root and parent), "parent-child" (parent and child), or "pure child" (child). |
| program | A "program" is a Yargs instance wrapped in a [Proxy][42] granting the instance an expanded set of features. Programs are represented internally by the [Program][43] type. |
| root | The tippy top command in your hierarchy of commands and the entry point for any Black Flag application. Also referred to as the "root command". |
| default command | A "default command" is [Yargs parlance][44] for the CLI entry point. Technically there is no concept of a "default command" at the Black Flag level, though there is the _root command_. |
$3
Expand details
I love Yargs 💕 Yargs is the greatest! I've made dozens of CLI tools with Yargs,
each with drastically different interfaces and requirements. Some help manage
critical systems.
As I was copying-and-pasting some configs from past projects for yet another
tool, I realized the (irritatingly disparate 😖) structures of my CLI projects
up until this point were converging on a set of personal conventions around
Yargs. And, as I'm [always eager][45] to ["optimize" my workflows][46], I
wondered how much common functionality could be abstracted away.
The goal: make my CLIs more stable upon release, much faster to build, and more
pleasant to test. And also avoid Yargs's most egregious footguns. But perhaps
most important: I wanted CLIs that would remain simple and consistent to
maintain.
Throw in a re-watch of the PotC series and Black Flag was born! 🏴☠🍾
$3
This is a [CJS2 package][x-pkg-cjs-mojito] with statically-analyzable exports
built by Babel for use in Node.js versions that are not end-of-life. For
TypeScript users, this package supports both "Node10" and "Node16" module
resolution strategies.
Expand details
That means both CJS2 (via require(...)) and ESM (via import { ... } from ...
or ) source will load this package from the same entry points
when using Node. This has several benefits, the foremost being: less code
shipped/smaller package size, avoiding [dual package
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$3
See [LICENSE][x-repo-license].
Contributing and Support
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are always welcome and greatly appreciated! 🤩** Just as well, you can [star 🌟
this project][x-badge-repo-link] to let me know you found it useful! ✊🏿 Or [buy
me a beer][x-repo-sponsor], I'd appreciate it. Thank you!
See [CONTRIBUTING.md][x-repo-contributing] and [SUPPORT.md][x-repo-support] for
more information.
$3
Thanks goes to these wonderful people ([emoji
key][x-repo-all-contributors-emojis]):
 Bernard 🚇 💻 📖 🚧 ⚠️ 👀 | ||||||
 Add your contributions | ||||||
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[1]: https://yargs.js.org
[2]: https://yargs.js.org/docs#api-reference-commanddirdirectory-opts
[3]: https://github.com/yargs/yargs/issues/1306
[4]: https://github.com/yargs/yargs/issues/1269
[5]: https://github.com/yargs/yargs/issues/1975
[6]: https://github.com/yargs/yargs/issues/2152
[7]: ./docs/features.md#declaratively-build-deep-command-hierarchies-
[8]: ./docs/features.md#convention-over-configuration-
[9]: ./docs/features.md#its-yargs-all-the-way-down-
[10]: ./docs/features.md#built-in-support-for-dynamic-options-
[11]: https://github.com/yargs/yargs/issues/793
[12]: https://github.com/yargs/yargs/issues/2119
[13]: https://github.com/yargs/yargs/issues/2256
[14]: https://github.com/yargs/yargs/issues/2227
[15]: https://github.com/yargs/yargs/issues/2133
[16]: ./docs/features.md#run-your-tool-safely-and-consistently-
[17]: ./docs/features.md#simple-comprehensive-error-handling-and-reporting-
[18]: ./docs/features.md#a-pleasant-testing-experience-
[19]: ./docs/features.md#extensive-intellisense-support-
[20]: #quick-start
[21]: ./docs/getting-started.md
[22]: ./docs/bf-vs-yargs.md
[23]: https://github.com/Xunnamius/black-flag-demo
[24]: ./examples/README.md
[25]: ./examples/yargs-intro/README.md
[26]: https://github.com/yargs/yargs/blob/HEAD/docs/examples.md
[27]: https://yargs.js.org/docs#api-reference-optionskey-opt
[28]: ./docs/api/src/exports/type-aliases/Configuration.md
[29]: ./docs/api/src/exports/type-aliases/ConfigurationHooks.md
[30]:
./packages/extensions/docs/index/type-aliases/BfeBuilderObjectValueExtensions.md
[31]: ./docs/api/src/exports/README.md
[32]: ./docs/api/src/exports/util/README.md
[33]: ./packages/extensions/docs/index/README.md
[34]: ./packages/checks/docs/index/README.md
[35]: ./packages/extensions/README.md
[36]: ./docs/bf-vs-yargs.md#irrelevant-differences
[37]: ./packages/checks/README.md
[38]: https://yargs.js.org/docs#api-reference-checkfn-globaltrue
[39]: ./docs/advanced.md
[40]: https://github.com/yargs/yargs/blob/main/docs/tricks.md
[41]: ./docs/api/README.md
[42]:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
[43]: ./docs/api/src/exports/util/type-aliases/Program.md
[44]: https://github.com/yargs/yargs/blob/main/docs/advanced.md#default-commands
[45]: https://xkcd.com/1205
[46]: https://i.redd.it/0cm6yx27tez21.jpg