Re: Improvements to adjust-parens

[Ryan C. Thompson]

Replies in line below:

On 11/26/2013 03:04 PM, Barry OReilly wrote:
>        (and (not (use-region-p))
> -           (<= orig-pos (point))))))
> +           ;; Corrent line is properly indented
> +           (= (current-column)
> +              (let ((indent (calculate-lisp-indent)))
> +                (if (listp indent)
> +                    (car indent)
> +                  indent)))
> +           ;; Point at indentation
> +           (= orig-pos (point))))))
>
> Revising the diff to account for nil indent and to put the most
> expensive check last:
>
> -      (and (not (use-region-p))
> -           (<= orig-pos (point))))))
> +      (and (= orig-pos (point))
> +           (not (use-region-p))
> +           ;; Corrent line is properly indented
> +           (let ((indent (calculate-lisp-indent)))
> +             (and indent
> +                  (= (current-column)
> +                     (if (listp indent)
> +                         (car indent)
> +                       indent))))))))

Sounds good. Also change "corrent" to "current". That's probably a typo 
on my part.

> Regarding:
>
> +       ;; Only pass an explicit numeric prefix, not `C-u' prefix.
> +       (unless (listp parg)
> +         (prefix-numeric-value parg)))
>
> What sort of use cases do prefix args as lists normally serve? From
> what I see, they come in powers of four, which doesn't seem applicable
> to adjust-parens. The Elisp manual entry doesn't really cover the
> "why" of this kind of prefix arg.

I believe the "C-u" prefix is passed as a list just so you can tell the 
difference between e.g. "C-4" and "C-u", i.e. a numeric vs generic 
prefix argument. I don't think there is ever more than one element in 
the list. In any case, you can make the prefix arguments work however 
you want.

> +  (cl-callf or parg 1)
> +  ;; Negative prefix arg inverts the behavior
> +  (when (< parg 0)
> +    (setq parg (- parg)
> +          adjust-function
> +          (cl-case adjust-function
> +            (adjust-close-paren-for-indent 
> 'adjust-close-paren-for-dedent)
> +            (adjust-close-paren-for-dedent 
> 'adjust-close-paren-for-indent)
> +            (otherwise (error "Unknown adjust-function: %s" 
> adjust-function)))))
> +  (when (> parg 0)
>
> Processing negative prefix arg makes sense. I think it is cleaner to
> do it one level higher and pass the right function as the
> adjust-function argument. eg:
>
>   (adjust-parens-and-indent
>    (if (< parg 0)
>        'adjust-close-paren-for-dedent
>      'adjust-close-paren-for-indent)
>    (abs parg))

That's fine. I just did the first thing that worked.

> +    ;; Move forward (but not back) to end of indentation (but don't
> +    ;; change the indentation unlike `indent-for-tab-command'.
> +    (when (< (current-column) (current-indentation))
> +      (back-to-indentation))))
>
> I figured since <backtab> is unbound in 'emacs -Q', adjust-parens
> should do nothing in this case. The analogous <backtab> in Python
> appears to also do nothing if it does not dedent.
>
> It might be easier to decide what to do here with better perspective
> about how people use <backtab>.

I forget what my logic was here. Feel free to do whatever you think is 
appropriate. I think backtab is actually not used in many modes.
> +(define-globalized-minor-mode global-adjust-parens-mode 
> adjust-parens-mode
>            (lambda ()
> -            (local-set-key (kbd "TAB") 'lisp-indent-adjust-parens)
> -            (local-set-key (kbd "<backtab>") 
> 'lisp-dedent-adjust-parens)))
> +    ;; Add or remove hook
> +    (funcall (if global-adjust-parens-mode #'add-hook #'remove-hook)
> +             'after-change-major-mode-hook
> +             #'adjust-parens-after-change-mm-hook)
> +    ;; Run the hook in existing buffers to enable/disable the mode
> +    (dolist (buf (buffer-list))
> +      (with-current-buffer buf
> +        (adjust-parens-after-change-mm-hook)))))
>
> adjust-parens doesn't seem global in nature, so I'm uncertain about
> the choice of a global minor mode. I think a local minor mode makes
> sense though. Then the user would enable it in major modes by eg:
>
>   (add-hook 'emacs-lisp-mode-hook #'adjust-parens-mode)

The global mode isn't really "global". It only activates in buffers with 
approved major modes. This is essentially a way for users who do all 
their customization through M-x customize to auto-enable adjust-parens 
in specific modes, by enabling the global mode and then customizing 
"adjust-parens-enabled-major-modes".