Optionally specify callback to cider load buffer

[magnars]

• cider-load-buffer (normally bound to C-c C-k) does not pass a callback to cider-request:load-file. With this change, a user can now optionally specify this callback.

• when no callback is passed to cider-request:load-file, it will fall back on cider-load-file-handler, which does not specify a done-handler. With this change, a user can now optionally specify a done-handler.

These two changes together would allow users to perform some task after loading the current buffer, by doing something like this:

(cider-load-buffer nil (cider-load-file-handler nil (lambda (&rest _) (message "I'm done!"))))

In my case that would be running tests.

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Thanks!

If you're just starting out to hack on CIDER you might find this section of its
manual extremely useful.

[bbatsov]

Nice idea! Let me think a bit about this, as there's another approach to do the same thing - namely trigger some hook functions in the done handler, which might be more user-friendly.

[bbatsov]

Let me also ping @Malabarba here, as back in the day he had a different approach to this https://endlessparentheses.com/test-driven-development-in-cider-and-emacs.html

[bbatsov]

Hmm, actually I see we already have the file loaded hook, but it's being triggered in another handler (the value handler). I'm not sure if this has any practical differences, so I guess you can help me understand why using the done callback is preferable for this.

[magnars]

I'm happy to use the cider-file-loaded-hook for my use case. I just didn't notice it there, since I was thinking in callbacks. :) I still see some use cases for this change, in that hooks are global. When passing in the callback you can affect only this invocation, without having to juggle un-registering hooks afterwards.

[magnars]

As a side note, the trick @Malabarba uses is the one I'm trying to avoid here - since I had to resort to a (reset) in my save-handler, which doesn't scale well with project size.

[bbatsov]

Btw, I've noticed one small problem with our existing hook - starting with nREPL 0.6 you can actually get multiple value responses (chunks of the same result). While this is unlikely to affect ns loading, it might also be better to move the triggering of the hook to the done handler as well.

When passing in the callback you can affect only this invocation, without having to juggle un-registering hooks afterwards.

Yeah, that's a perfectly valid argument.

[Malabarba]

since '() is the same as nil, this whole line is the same as just done-handler

[Malabarba]

I think it's reasonable for the function to receive a callback argument, since it's already implemented in the lower functions. I think both the hook and the local callback will probably have its uses in different situations.

[bbatsov]

@Malabarba Fine by me. Let's get this baby merged! Btw, do you think we should move the hook in the done handler as well?

@magnars Please, add a changelog entry for the PR.

[magnars]

Done, as well as freshly rebased onto master.

[bbatsov]

Thanks!