Re: (interactive) and &optional

[Jean Louis <bugs@gnu.support>]

* Philip Kaludercic <philipk@posteo.net> [2023-03-24 23:54]:
> > I do not like involving `interactive' at all, so I do the handling by
> > providing optional argument and telling function to check for it, or
> > ask for it.
> >
> > (defun search-something (&optional query)
> >   "Search something by using QUERY."
> >   (interactive)
> >   (let* ((query (or query (read-from-minibuffer "Query: "))))
> >     (do-the-search query)))
> 
> The issue here is that the function is difficult to re-use from other
> scripts.  If the interactive stuff is encapsulated within an
> (interactive) form then you avoid the issue.

I understand the meaning in general, though I do not understand what
is the mentioned issue. Could you explain it?

It is interesting as I use those functions from other functions.

This should be the classic Emacs Lisp approach:

(defun search-something (query)
   "Search something by using QUERY."
   (interactive "MQuery: ")
   (message query))

(progn (search-something "Hello")) ➜ "Hello"
(progn (search-something)) ➜ "Ok here"

This should be my approach:

(defun search-something (&optional query)
   "Search something by using QUERY."
   (interactive)
   (let ((query (or query (read-from-minibuffer "Query: "))))
     (message query)))

(progn (search-something "Hello")) ➜ "Hello"
(progn (search-something)) ➜ "Ok here"

- while `interactive' declaration may shorten some code, it may as
  well complicated readability of function

Here is short version where buffer must be existing buffer:

(defun my-message-buffer (buffer)
  "Message name of my BUFFER."
  (interactive "b")   
  (message buffer))

That short function I do not know how to make easy without (interactive "b"). 

For majority of uses in my code I do not use arguments to
`interactive' and there are no issues so far.

I find `interactive' complex and would like to know why it was
invented.

(info "(elisp) Using Interactive")
(info "(elisp) Interactive Codes")

Tell me examples on what issues you encounter and pointers to
implications.

-- 
Jean

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