communication between tasks

[davidpfahler]

This problem became apparent in a discussion on the grunt-contrib-watch repository. The issues there was that the watch task can not tell other tasks which files where changed and triggered the watch task to run them.

This shows a general problem in grunt and that is the missing communication infrastructure between tasks. grunt.event provides a good technical implementation and I personally think events are the way to go. But what we need is a solid convention so everybody knows how grunt plugins can be talked to.

I hope we can start a discussion about this matter here.

[cowboy]

Tasks are generally atomic. No task, in general, needs to know about any other task. It just needs to know about its configuration.

That being said, one way for task A to tell task B what to do is to create a custom target inside task B's configuration data, then run task B with that target name. Then task B doesn't need to know that task A exists, it just needs to read its configuration data.

If you are writing multiple tasks that need to communicate with one another, you can always use a shared variable or tempfile. There is no convention because generalized inter-task communication has never been necessary.

[steida]

Can be custom target of task B dynamically created from task A? We really need it. Nobody want to run all tests or compile zilion coffee scripts at exactly one file change.

[cowboy]

This approach is what I'm currently experimenting with:

That being said, one way for task A to tell task B what to do is to create a custom target inside task B's configuration data, then run task B with that target name. Then task B doesn't need to know that task A exists, it just needs to read its configuration data.

[davidpfahler]

@steida that's what I'm talking about.
@cowboy This is exactly the kind of convention or abstract generalization I'm hoping to see. I just want a way that is the standard which everybody can conform to and everybody's happy :)

[shama]

It's not an ideal solution but here is an example that modifies your config to run only on modified files: gruntjs/grunt-contrib-watch#65 (comment)

[Athaphian]

I was also thinking about this today when experimenting with websockets. I have started a grunt-contrib-connect configuration, but there does not seem to be any way to attach a websockets server to the already running server, because the connect task does not expose the underlying server object in any way. So currently I'm stuck with serving websockets on a different port, which is sub optimal.