[Emacspeak] Ergonomic Buffer Select On The Emacspeak Audio Desktop

["T.V Raman" <raman@xxxxxxxxxx>]

https://emacspeak.blogspot.com/2023/07/ergonomic-buffer-selection-on-emacs.html
* Background

Buffers are central to Emacs as is evinced by the various
buffer-selection schemes that have been created over time. As someone
who has lived for over 30 years in Emacs, my own set of
buffer-selection tools have evolved and I've settled on a combination
of /ido/ and /fuzzy matching/ over the last few years. This article
describes a new tool that puts all of these together,  but with an emphasis on
ergonomics and minimized chording.

* Setting The Context

Buffer selection tools in Emacs vary along the following feature axis,
with many providing enhancements on one ore of  these axis:

  - Match Strategy: Selecting the buffer name from the available choices,
  - UI: Displaying those matches,
  - And finally displaying the buffer.

    Command /emacspeak-buffer-select/  focuses exclusively on invocation
    and keyboard commands for moving through the choices and selecting
    the buffer.

    * So Why Is Ido  Not Sufficient?

      Package /ido/ is still my tool of   choice and has served me well
      over the years. The problem /emacspeak-buffer-select/ solves is  along the
      invocation axis; it can be traced back to my desire to avoid
      chording, and in that context, I found that _C-x b_ was becoming
      particularly irksome. The solution described below is
      specifically optimized to my current configuration using 
[[https://emacspeak.blogspot.com/2023/02/enhance-emacs-ergonomics-under-x-happy.html][XCape]], where  a single tap on the _CTRL/Caps_Lock_ key produces
Emacspeak prefix _C-e_.

* Design Goals

  - No chording.
  - Enable moving through list of buffers with  pairs of related keys.
  - Enable various types of ordering of the available choices e.g.,
    navigate by major-mode.
  - In the spirit of /ido/, enable falling through to
    _switch-to-buffer_ and _find-file_ when needed.
  - Following on from above, enable relevant actions like killing buffers.

* Use _set-transient-map_ To Implement The Behavior

In the past I would have implemented the above using package /hydra/
or /transient/; But both felt overweight for this case. My final
solution uses Emacs builtin _set-transient-map_.

* Final Behavior

  - Command _emacspeak-buffer-select_ is invoked via keys _C-e ,_,
   _C-e ._, _C-e n_, and _C-e p_.
  - That command  moves to the *next/previous* buffer.
  - The key pair _, ._ use Emacs commands _previous-buffer_ and
    _next-buffer_; keys _n_ and _p_ pick the previous or next buffer
    that uses the current buffer's major-mode.
  - In addition, while active, the transient-map binds:
    - b: _switch-to-buffer
    - k: _kill-buffer_
    - o: _other-window_
      
With the above in place, my most common workflows look like:

  - Press   _,_ or _._ repeatedly to cycles through next/previous buffers.
  - Press _n_ or _p_ repeatedly to  cycle through buffers in the same
    mode, especially useful when programming, or using EWW to browse
    the Web.
  - Press _b_ or _f_  when cycling doesn't yield the target in a couple of steps.
  - Opportunistically clean up unwanted buffers by pressing _k_.

You can see the final implementation at [[https://github.com/tvraman/emacspeak/blob/master/lisp/emacspeak-speak.el#L2839][emacspeak-buffer-select]]. Note
that despite the naming there is little that is specific to Emacspeak
in the above.

** Emacspeak Specific Features

  - Uses Auditory icons to indicate that a transient map is active.
  - Produces an auditory icon when the transient map goes away
  - Uses _call-interactively_ to invoke subcommands so that they
     automatically produce auditory feedback via Emacspeak.