Casual IBuffer

An opinionated Transient-based menu for IBuffer, a buffer management tool for Emacs.

Motivation

While highly functional, IBuffer has a steep learning curve as it has a very diverse command set. Menus are a user interface (UI) affordance that offer users discoverability and recall that can lower IBuffer’s learning curve. While menus are commonly associated with mouse-driven UI, the inclusion of Transient in Emacs core allows for a menu UI that is keyboard-driven. Casual IBuffer endeavors to offer this as many Emacs users prefer keyboard-driven workflows.

Goals

• To provide a keyboard-driven menu UI for IBuffer.
• To provide casual access to the IBuffer command set.

Non-Goals

• Full coverage of all IBuffer commands. Casual IBuffer is not intended to be a power user tool.
• Strict adherence to IBuffer command naming. While Casual IBuffer is mostly in alignment with IBuffer’s command naming, there are cases where it will make an opinionated change if the name is deemed too vague or idiomatic.
• UX Stability (for now). Given that Casual IBuffer is early in its life-cycle, expect changes to its user experience in terms of menu hierarchy and keybinding choices in future releases.

Requirements

Casual IBuffer has been verified with the following configuration.

• Emacs 29.3 (macOS 14.5, Ubuntu Linux 22.04.4 LTS)

Asks

As Casual IBuffer is new, we are looking for early adopters! Your feedback is welcome as it will likely impact Casual IBuffer’s evolution, particularly with regards to UI.

Install

If installed via MELPA then add these lines to your Emacs initialization file with your binding of preference.

(require 'casual-ibuffer) ;; optional
(keymap-set ibuffer-mode-map "C-o" #'casual-ibuffer-tmenu)
(keymap-set ibuffer-mode-map "F" #'casual-ibuffer-filter-tmenu)
(keymap-set ibuffer-mode-map "s" #'casual-ibuffer-sortby-tmenu)

If you use use-package, here is the recipe for installing it.

(require 'ibuffer)
(use-package casual-ibuffer
  :ensure t
  :bind (:map ibuffer-mode-map
              ("C-o" . casual-ibuffer-tmenu)
              ("F" . casual-ibuffer-filter-tmenu)
              ("s" . casual-ibuffer-sortby-tmenu)))

Casual requires Emacs 29.1+.

Configuration

Use these keybindings to configure IBuffer to be consistent with keybindings used by Casual IBuffer.

(keymap-set ibuffer-mode-map "{" #'ibuffer-backwards-next-marked)
(keymap-set ibuffer-mode-map "}" #'ibuffer-forward-next-marked)
(keymap-set ibuffer-mode-map "[" #'ibuffer-backward-filter-group)
(keymap-set ibuffer-mode-map "]" #'ibuffer-forward-filter-group)
(keymap-set ibuffer-mode-map "$" #'ibuffer-toggle-filter-group)  

While not necessary for Casual IBuffer, enabling hl-line-mode and binding mouse clicks in IBuffer adds to a more comfortable IBuffer experience. Also, adding ibuffer-auto-mode to ibuffer-mode-hook will enable auto-updating.

(require 'hl-line)
(require 'mouse)
(add-hook 'ibuffer-mode-hook #'hl-line-mode)
(add-hook 'ibuffer-mode-hook #'ibuffer-auto-mode)
(keymap-set ibuffer-mode-map "<double-mouse-1>" #'ibuffer-visit-buffer)
(keymap-set ibuffer-mode-map "M-<double-mouse-1>" #'ibuffer-visit-buffer-other-window)

Usage

Casual IBuffer organizes commands into three menus:

1. The main menu (casual-ibuffer-tmenu) holding commands for marking and operating on buffers. Display, find/replace, and navigation commands are also included in this menu.
2. The filter menu (casual-ibuffer-filter-tmenu) holding commands for defining filters, filter groups, and collections of filter groups.
3. The sort menu (casual-ibuffer-sortby-tmenu) holding commands for sorting buffers.

Marking and Operating

Buffers can be marked using different criteria. Marked buffers can be operated on. Common operations include saving and deleting buffers. Note that deleting a buffer populated with a visited file is not the same as deleting the visited file.

From the main menu shown above, control of the display and find/replace operations are offered.

Note that the menu item Visit/Toggle has “do what I mean” (DWIM) behavior. If the point is currently on a filter group (described below) then pressing the return key will toggle the visibility of items matching that filter group. Otherwise, it will visit (open) the buffer.

As with other Casual porcelains, the ability to jump to a bookmark is available.

Filtering

IBuffer is embarrasingly rich in the ways it can filter buffers. Once mastered, IBuffer filtering offers a way to create different views on your buffer list, enabling you to tailor bespoke views for different workflows. Such capability comes with a price though: you’ll need to understand how IBuffer wants to organize filters.

Key is the concept of a Filter Group which is IBuffer’s analog to a Dired subdirectory (subdir). But whereas a subdir only maps to a file system directory, a filter group can be constructed from a diverse set of rules to categorize a buffer.

IBuffer organizes filtering with the following taxonomy:

1. Filter rule

   The smallest unit of filtering. There are many types of filter rules:

   • filter by major mode
   • filter by derived mode
   • filter by buffer name
   • filter by buffer content
   • filter by basename
   • filter by directory name
   • filter by filename
   • filter by file extension
   • filter by modified buffers
   • filter by an arbitrary Lisp predicate
   • filter by buffer size
   • filter by special buffers
   • filter by buffers visiting files

     Casual IBuffer makes the design decision to not enumerate the above in a menu, delegating the work of filter selection to the command ibuffer-filter-chosen-by-completion.

2. Filter

   A filter is a logical combination of filter rules. Logic operators such as AND (&), OR (|) and NOT (!) are used to compose rules into a filter. A single filter rule can also be construed as a filter.

   Properties of filters:

   • A filter can be defined and saved for subsequent use.
     • Filters are saved in the customizable variable ibuffer-saved-filters.
     • Multiple filters can be applied at the same time to a set of buffers.
   • Multiple filters are applied in LIFO order. Removing a filter is a “pop” operation.
     • Rules that are combined with a logic operator are treated as a single element of the LIFO stack.
     • To individually edit the combination, use the Decompose command to remove the logic operator first.
3. Filter Group

   A filter group is set of filters. The set itself is named with an identifier that is user-defined.

   Properties of filter groups:

   • A filter group can be defined and saved for subsequent use but with a special qualifier:
     • Filter groups are only saved as a collection (more below) in the customizable variable ibuffer-saved-filter-groups. A filter group can not be saved individually.
   • Multiple filter groups can be applied to partition the buffer list.
   • Multiple filter groups are applied in LIFO order. Removing a filter group is a “pop” operation.
     • Similar LIFO and decompose behavior applicable to a filter group is supported.
4. Filter Group Collection

   A collection is a set of filter groups that can be named with a user-defined identifier. Only one collection can be applied to a buffer list at a time. However, many different collections can be defined, allowing for different views of the same buffer list.

Creating Filters

The basic procedure for making a filter that applies to the entire buffer list is as follows:

1. From the Filter menu, create a filter via (SPC) Rule… and some desired combination of operators.
2. Save the filter via (s) Save…. You will be prompted to provide a name for the filter. This filter will be saved in the variable ibuffer-saved-filters.
3. To recall this filter at a subsequent time, use (r) Switch to… in the Add section of the Filter menu.

Creating a Collection of Filter Groups

Here is where the taxonomy becomes significant as the IBuffer command set unfortunately does not provide much observability on edit operations to filters.

1. Create a filter as described above.
2. In the Add section of the Filter menu, select (g) Create Filter Group… to convert the filter into a filter group. You will be prompted to name the filter group. This group name will be enclosed by square brackets [].
3. Multiple filter groups can be created by repeating steps 1 and 2 above. Note that when constructing a filter group, the IBuffer window will not provide observability of existing filter groups on the buffer list.
4. You can save the set of filter groups as a collection in the Collection section with the command (S) Save…. You will be prompted to name the collection. Note that only one collection can be used at a time in IBuffer.

Out of the box, it is best to think of the IBuffer commands for editing buffer filters as a kit of parts and an arguably incomplete one at that. The Casual IBuffer filter menu (casual-ibuffer-filter-tmenu) is my attempt to build a comprehensible filter editor UI from this kit. Whether it succeeds in being comprehensible is left to user feedback.

Sorting

The buffer list can be sorted using different criteria as shown in the screenshot above.

Sort ordering can be reversed via the Invert command.

Unicode Symbol Support

By enabling “Use Unicode Symbols” from the Settings menu, Casual IBuffer will use Unicode symbols as appropriate in its menus. The following mapping is shown in the table below:

Name	Plain	Unicode
:previous	Previous	↑
:next	Next	↓
:marked	Marked	❯
:group	Group	[]
:jump	Jump	🚀

Common Menu Actions

Casual IBuffer is built using Transient menus and as such adopts much of its default behavior.

Each menu item has a key and a label. The key is what is typed by the user to select the menu item. A key can be prefixed with a meta (M-) or control (C-) key.

Dismissing a menu regardless of how deep you are in sub-menus can be done by entering C-q. A menu can also be dismissed by entering C-g, but this will return you to the parent menu.

If a mouse is available, a menu item can be selected by moving the mouse cursor over its label and pressing down button 1.

Pressing the ? key will toggle help for all the menu items. Press the key of interest to get help for it.

Options such as --above and --below can be saved for future use by typing C-x C-s.

When a Transient menu is raised, a prefix argument (C-u) can be entered before selecting a menu item.

Development

For users who wish to help contribute to Casual IBuffer or personally customize it for their own usage, please read the developer documentation.

Sponsorship

If you enjoy using Casual IBuffer, consider making a modest financial contribution to help support its development and maintenance.

See Also

Casual IBuffer is part of a suite of porcelains for different Emacs packages.

To get all current and future Casual porcelains, please install Casual Suite from MELPA.

Porcelains currently supported by Casual are listed below:

• Casual Avy - a Transient porcelain for Avy.
• Casual Calc - a Transient porcelain for Calc.
• Casual Dired - a Transient porcelain for Dired.
• Casual Info - a Transient porcelain for the Info reader.
• Casual I-Search - a Transient menu for I-Search.

Users who prefer finer grained control over package installation can install each porcelain above individually.

Acknowledgments

A heartfelt thanks to all the contributors to IBuffer and Transient. Casual IBuffer would not be possible without your efforts.