Accessing arg with (interactive "P")

[carlmarcos]

I have the following elisp function, using `current-prefix-arg` to decide 
subsequent processing.

Having made the command examine it directly, the usual method for accessing it 
is with 
(interactive "P").  The problem is that I do not know how to examine the prefix 
arg through
 the interactive clause.

(defun poke (&optional prefix)
  "TODO"

  (interactive "P")

  (cond
   ((equal current-prefix-arg nil)   ; no C-u
    (setq workbench-poke-name-mode 1))

   ((equal current-prefix-arg '(4))  ; C-u
    (arktika-workbench))