How to use :show-help when defining a new prefix?

[Munksgaard]

I'm trying to define a new prefix for a command that doesn't have a man-page, but I'm having trouble figuring out how :show-help is supposed to be used. Ideally, I'd just want it to show the output of mycommand --help in a buffer, but I can't find any examples anywhere of how to do that.

This is what I have so far:

(transient-define-prefix gt-create ()
  "Create a new branch"
  :show-help (lambda (obj) (debug(obj)))
  ["Arguments"
   ("-a" "Stage all unstaged changes before creating the branch, including to untracked files." "--all")]
  ["Actions"
   ("a" "Create" gt-create)]
  (interactive)
  (transient-setup 'gt-create))

Which gives me the following output in my messages:

transient-help: (void-function obj)
Unbound suffix: ‘?’ (Use ‘C-g’ to abort, ‘?’ for help) [transient-help]

[tarsius]

The error message is due to a defect in your code that has nothing to do with Transient:

(lambda (obj) (debug (obj))
==error==> (void-function obj)

obj is in "function position" and thus called as a function, but there is no function named obj here, just a variable by that name.

What you probably wanted to do is:

:show-help (lambda (obj) (message "Let's test what obj looks like: %S" obj))

[Munksgaard]

You're right, thank you very much.

[tarsius]

(Meta: Note that there are multiple "reply text areas". In this case you should have used the other one.)

Last night I've written some code to make this sort of thing easier. I'm out the door now, but will finish it later.

[Munksgaard]

Amazing! I'll look forward to it.

For context, I am trying to write some (very light) magit-like functionality for the Graphite CLI, so I'm basically just trying to show the result of e.g. gt create --help.

[tarsius]

If added a new macro for this in 5fcd713, along with some documentation. A basic example:

(transient-define-prefix demo ()
  :show-help (lambda (_)
               (transient-with-help-window
                 (process-file "ls" nil t nil "--help")))
  [(transient-echo-arguments)])

[Munksgaard]

That's exactly what I needed, thank you very much!

[tarsius]

You're welcome.

This also got me to revisit an old kludge, see 732ec97.