magit purpose defined by purpose-x-magit can cause error: Wrong number of arguments: (0 . 2), 3

[qleguennec]

The following configuration gives me the error: Wrong number of arguments: (0 . 2), 3 when I call switch-to-buffer or magit:

(use-package window-purpose
  :demand t
  :config
  (purpose-mode)
  (require 'window-purpose-x)

  (setq pop-up-frames t)
  (purpose-x-magit-single-on)
  (add-to-list 'purpose-special-action-sequences
	       '(magit
		 purpose-display-reuse-window-buffer
		 purpose-display-reuse-window-purpose
		 purpose-display-pop-up-frame)))

emacs version: 27.0.50

[bmag]

When you put magit in purpose-special-action-sequences like this, because a function named magit exists, Purpose interprets it as a predicate functions and calls it with 3 arguments.

The problem here is in the purpose-x-magit extension - I should change it to define a Magit purpose instead of magit, then you can put Magit instead of magit. In the meantime you can replace magit with (lambda (purpose _buffer _alist) (eq purpose 'magit)).

I'm gonna change the title to reflect the bug (it is unrelated to Emacs version).

[bmag]

Should be fixed by 34b4d08. You will need to replace magit with Magit in purpose-special-action-sequences.