Support hooks befor/after execute run func

[tmg0]

Describe the feature

Add defs in defineCommand function like interceptors or middlewares

example:

const customInterceptor1 = (ctx: CommandContext) => false
const customInterceptor2 = (ctx: CommandContext) => console.log('before run.')

defineCommand({
  meta: {
    name: "hello",
    version: "1.0.0",
    description: "My Awesome CLI App",
  },
  interceptors: [customInterceptor1, customInterceptor2]
  run({ args }) {
    // output: before run.
    // and this code will not be execute
    console.log(`${args.friendly ? "Hi" : "Greetings"} ${args.name}!`);
  },
})

Additional information

• Would you be willing to help implement this feature?

[NozomuIkuta]

It sounds reasonable by itself to support a way to run some logic before/after main logic.

Actually, other UnJS packages also have "hooks" options (e.g. Nitro) or onXYZ interceptors options (e.g. h3, ofetch) to do something before/after some logic.

The difference between these and your code is that your interceptors can abort the command execution, rather than making a side effect and/or modifying options passed.

So, to clarify, do you want to have "validators" to determine if the command should be run, and want to separate them as another option instead of writing them inside of run method body for better code organization?

[tmg0]

Actually what I need is a hook, such as checking the version of the CLI before/after run the main logic with a better code organization.

I'm not sure if determining whether to abort through the return value is a good idea, but it seems quite convenient.

Maybe add a abort callback function in CommandContext is a better way?

e.g.

const before= ({ abort }: CommandContext) => {
  const isLatest = version === "1.0.0"
  if (!isLatest) { abort() }
}

const after= () => { console.log('after run.') }

defineCommand({
  meta: {
    name: "hello",
    version: "1.0.0",
    description: "My Awesome CLI App",
  },
  before,
  run({ args }) {
    console.log(`${args.friendly ? "Hi" : "Greetings"} ${args.name}!`);
    // output: after run
  },
  after,
})

[tmg0]

Emmmmm, It seems unnecessary to add a abort callback, in before hook can just throw an error to terminate the logic.

[peterroe]

It seems like your needs can be completely solved by setup/cleanup, maybe we need an idea with a clearer function orientation 👀

[jgoux]

A middleware system would be super useful for stuff like telemetry:

const telemetryMiddleware = async (ctx, next) => {
  await telemetry.captureEvent(`$command:${ctx.cmd.meta.name}:start`); 
  await next(ctx);
  await telemetry.captureEvent(`$command:${ctx.cmd.meta.name}:end`);
}

defineCommand({
  meta: {
    name: "hello",
    version: "1.0.0",
    description: "My Awesome CLI App",
  },
  middlewares: [telemetryMiddleware],
  run({ args }) {
    console.log(`${args.friendly ? "Hi" : "Greetings"} ${args.name}!`);
  },
})

The idea would be that the run handler would be passed to the middleware chain defined in middlewares.

[pi0]

@jgoux having a context-full api makes sense. I think i have a better idea inspired from your usecase to introduce with plugins ~> #130