Build action_cable.js with Blade

[javan]

• Compiles action_cable.js with Blade, which essentially uses the same Sprockets setup we had in the rake task. No need to duplicate.
• Uses sprocket-export's #= export directive to replace the somewhat incomplete implementation

/cc @maclover7 @jeremy

[matthewd]

Does this make blade a runtime requirement for anyone running out of a git clone?

[javan]

No. Unknown Sprockets directives are ignored so without Blade the default behavior applies (setting window.ActionCable).

[matthewd]

I think I'd prefer to keep this in a form amenable to hackery -- I know it's Bad, but I'll often open a file in an installed gem to install a temporary puts; retaining the ability to do the same with console.log seems desirable... especially as it doesn't really matter -- it'll be compressed eventually either way.

(Bonus argument: if we pre-compress, sprockets + source-maps will leave this file unpleasant to debug even when everything else is nice and shiny.)

[javan]

For that kind of hackery, you could point to the uncompiled action_cable.coffee for inserting your console.logs, etc.

especially as it doesn't really matter -- it'll be compressed eventually either way

That's true if your app compresses assets, but it's not a given. Especially considering people can install via npm and use action_cable.js outside of Rails / Sprockets.

I don't feel strongly that it should be compressed given its relatively small file size, but it feels like the right thing to do for a distributed .js file. FWIW, Turbolinks is compressed using the same setup.

[matthewd]

For that kind of hackery, you could point to the uncompiled action_cable.coffee

The uncompiled file isn't there, though.

[vipulnsward]

For that kind of hackery, you could point to the uncompiled action_cable.coffee for inserting your console.logs, etc.

On npm most would prefer the JS/ES6 version. Even if they would use coffee version we don't ship with it right now on npm.

That's true if your app compresses assets, but it's not a given. Especially considering people can install via npm and use action_cable.js outside of Rails / Sprockets.

Anyone doing doing this will already be using compression by some other means.

Here's how our current npm package looks-

• https://monosnap.com/file/RdcH7bbAYS0dWP7N2FoX2JCkMflK3J

Here's some other examples from popular libraries-

• https://monosnap.com/file/QaCy3QX8z0ZIGqBUAAVTEc8jc6EbTQ
• http://take.ms/zLdpW

Most of them contain uncompressed + compressed version. Its ok to just ship with compressed one, since its essential for things listed by Matthew:

• sourcemaps
• edit/check source code of actual library
• source linking of methods, etc in editors

I don't feel strongly that it should be compressed given its relatively small file size, but it feels like the right thing to do for a distributed .js file

As seen above many libraries ship with both, so that they can be used as needed. For us its ok to ship just with unminified version as well.

[javan]

Ah, right. Forgot we only include lib in the gem.

Either way, I'm not sure your use case of editing an installed gem justifies distributing a larger than necessary .js file.

[javan]

I removed js compression for now (javan@27ae7c3), but I think we have it backwards. The reasons listed for using an uncompressed version are all development concerns so, if anything, we should provide an additional uncompressed version for debugging.

Turbolinks is part of the default stack and compresses its source so we're currently inconsistent about the js we bundle.

it doesn't really matter -- it'll be compressed eventually either way

Anyone doing doing this will already be using compression by some other means

You both seem pretty confident about this for some reason. Have you seen the... internet? 😁

[vipulnsward]

@javan ideally we should include both, as done by others, and provide option to use either one.
For me, it would be really important to have uncompressed version to check out the source, editor linking, source maps, etc. Again, this is because of how we develop right now, CS->JS. Other libs just include their source too, and
provide dist versions of compressed/uncompressed versions, minus the noise like tests.

Right now we are on edge and ironing things out, I sometimes need to do manual exports for npm(not ideal), for making it work in some occasions, or some others might need to, to suit their export systems, commonjs, amd, etc.

[maclover7]

Don't we still we need to define this task, and provide a way for the compiled file to be deleted? 😬

[rafaelfranca]

👍

[javan]

All the other gems define an empty "package:clean" task. Introduced in d6f2000. I think Action Cable was the only one to implement it. Can probably remove them all now. @matthewd?

[rafaelfranca]

Don't we still need to delete the compiled files?

[matthewd]

It was indeed the only one, because it's the only component that currently produces a temporary file to clean up. I don't see how a change in the mechanism we use to generate the file obviates such a task... but I agree there's no point leaving it here empty.

[javan]

Blade cleans up its own tmp files: https://github.com/javan/blade/blob/master/lib/blade/assets/builder.rb#L9

[javan]

Removed package:clean in af777bf6ae67c8ec3ef200415d238614fefef68e and updated assets:compile to ensure a clean path in db84cb439a2c85cdace279451caad4bf40f7eb33.

[javan]

I updated Blade to output the build process and handle cleaning the dist path:

$ bundle exec rake assets:compile
Building assets…
[removed] lib/assets/compiled/action_cable.js
[created] lib/assets/compiled/action_cable.js

[vipulnsward]

@javan I see some downgrades, are they intentional from blade? or the dropping of coffee-script versions, etc.

[javan]

These dependencies were all added recently in 61483b1 when Blade 0.5.1 was introduced. It turns out Thin (a dependency of Blade) doesn't work with event machine 1.2.0 so I backed away from it in javan/blade@62c8cb0. Blade also removed exact dependencies on coffee-script and sprockets to reduce conflicts with apps that have tighter requirements. So if we want specific versions, we should declare them.

[rafaelfranca]

Backported in 45083d8

[javan]

Thanks, @rafaelfranca! Is it possible to release actioncable-5.0.1 independently (to fix #25649) or are the Rails gems always released together?

[rafaelfranca]

They are always released together. If you see the rails.gemspec we ask for the same version of the subgems. https://github.com/rails/rails/blob/master/rails.gemspec#L28.

If it is a critical fix we can do a full release early, but this is more something to @matthewd decide since he is the release manager of the next release.

[javan]

Cool. I don't think it's critical.