bug#53126: 29.0.50; [PATCH] Lazy highlight/count when reading query-replace string, etc.

[Juri Linkov]

>> Or for asynchronous lazy-count a new hook needs to be run at the end
>> of isearch-lazy-highlight-buffer-update in addition to the call of
>> isearch-message.
>
> That's what the patch does (but with a variable pointing to a function
> instead of a hook, although this can be changed).  But note that it's
> not enough to do something “in addition to the call of isearch-message”;
> it's necessary to _suppress_ the call to isearch-message.

It would be great to use your new variable with a function
to show replacement counts in perform-replace.  IIUC,
let-binding isearch-lazy-count-display-function to
isearch-read-with-highlight-count will suppress isearch-message?

>> Maybe then this feature could be added to read-regexp or even
>> to read-from-minibuffer?  And activated by adding a setup function
>> to minibuffer-setup-hook like other minibuffer's features do, such as
>> icomplete-minibuffer-setup, minibuffer-depth-setup, 
>> rfn-eshadow-setup-minibuffer.
>
> This is what the patch does, with code of this kind:
>
> ```
> (let ((isearch-regexp t)
>       ;; Whatever else isearch / lazy-highlight settings might be needed
>       (isearch-lazy-count-display-function 
> #'isearch-read-with-highlight-count))
>   (minibuffer-with-setup-hook #'isearch-read-with-highlight-setup
>     (read-from-minibuffer "Type a regexp with preview: ")))
> ```
>
> There could be a convenience wrapper for this code, but I'm not sure
> that makes much sense, because isearch and lazy-highlight have too many
> parameters one might need to set so it's better to be explicit/flexible.

I meant using simply

  (add-hook 'minibuffer-setup-hook 'isearch-read-with-highlight-setup)

But it seems isearch-read-with-highlight-setup doesn't set
isearch-lazy-count-display-function.

>> Then maybe a new feature could be named e.g. "lazy-minibuffer"?

This feature has little to do with isearch.  This is why there are
efforts to move away from the prefix isearch- for lazy-related
functions and variables, so we have now:

  lazy-count-prefix-format
  lazy-count-suffix-format
  lazy-highlight-buffer
  lazy-highlight-buffer-max-at-a-time
  lazy-highlight-cleanup
  lazy-highlight-initial-delay
  lazy-highlight-interval
  lazy-highlight-max-at-a-time
  ...

There are still isearch-specific names like isearch-lazy-count
that enables lazy-count in isearch-mode.  What would be a similar
name for the minibuffer?  Maybe minibuffer-lazy-count?

Then the prefix isearch- needs to be removed from other names too,
e.g. isearch-lazy-count-display-function -> lazy-count-display-function
isearch-read-with-highlight-setup maybe to minibuffer-lazy-highlight-setup,
etc.