Support "Exclusive" Mode to execute a task without dependencies

[nlowe]

Cake (a similar tool for writing build scripts in C#) supports a flag called --exclusive. This lets Cake execute a specific task without executing its dependencies. This allows you to quickly re-test a specific task (for example, re-build a Docker container without re-running tests if you just changed the dockerfile) and is particularly well suited for build environments like Jenkins where you can separate tasks for visibility.

In most of the Cake projects we use, we wire up dependencies normally, so if a developer runs the Docker test, they restore packages, build code, and run tests. In our Jenkins file, we split each task to a separate stage (called with --exclusive) in Jenkins so you get nice timing information and better visibility in Blue Ocean.

Is this something Mage could potentially support? I'd be happy to look into sending a PR.

[natefinch]

This is a very interesting idea. I actually just unwired some dependencies at work because they're a little too slow to rerun every time.

I think this could be useful for non-critical dependencies.

I think I would call it -nodeps.

Go ahead and make a PR.

[natefinch]

ok, so like..... I know I said to do it, but I have thought about it sense then, and I think it's actually easy enough to do with existing tools (i.e. use an environment variable), that I don't think it's worth adding another whole flag for it.

Sorry to flip flop on this.