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Appendix A Emacs 28 Antinews ¶

For those users who live backwards in time, here is information about downgrading to Emacs version 28.2. We hope you will enjoy the greater simplicity that results from the absence of many Emacs 29.1 features.

• The implementation of overlays is back to its simple, time-proven storage in a pair of linear linked lists centered around some buffer position. No more fancy interval trees and suchlikes. Lisp programs that use overlays once again need to recenter overlays around the buffer position of interest, and display-related features should again make sure they don’t use too many overlays in a buffer, lest redisplay will be too slow.
• Several functions stopped the annoying conversion of quotes and key sequences by no longer calling substitute-command-keys. One prominent example is format-prompt and all its many callers. This makes the strings they produce much more predictable, returning to you, the Lisp programmer, control on which punctuation characters will appear in the text presented to the users. For similar reasons, the substitute-quotes function was deleted.
• The venerable buffer-modified-p function again reliably returns either nil or t, not any other confusing values.
• The support for ‘medium’ weight of fonts was dropped. Emacs now considers ‘medium’ and ‘regular’ weights to be the same. We believe this will simplify your font setup, since there’s no longer a need to worry about fonts that support ‘regular’ weight, but not the ‘medium’ one, or vice versa: either one will do!
• To reduce the amount of code in Emacs related to unimportant features, we’ve removed the function compiled-function-p. Lisp programs are expected to test explicitly for the relevant types of function objects: built-in, byte-compiled, and natively-compiled. For the same reasons we deleted the functions pos-bol, pos-eol, file-attribute-file-identifier, and quite a few others. We don’t expect anyone to miss those fancy functions.
• The timeout used by x-show-tip can no longer be specified by Lisp programs; it is hard-coded in the function. This will lead to a simpler, easier maintained code, and no one should want to control the timeout after which the tip pops down.
• The macro setopt was deleted; use customize-variable instead, or invoke the :set function from Lisp.
• We removed the lisp-directory variable, as the value can be easily deduced from other similar variables, like installation-directory and source-directory, each one when it’s relevant.
• To simplify code and reduce complexity, we deleted the functions get-display-property and add-display-text-property; use the generic get-text-property and put-text-property instead.
• Support for pinch input events and for modern drag-and-drop functionality on X was dropped. As you move back in time, these facilities will become less and less important, and will soon enough disappear, so there’s no reason to keep them in Emacs.
• To keep Emacs clean and elegant, we’ve removed the textsec.el library, with its facilities for checking whether some text is “suspicious”. We consider our users smart enough to detect maliciously modified text by just looking at it or by moving the cursor across it, and the whole idea that someone would wish to deliberately deceive Emacs users ridiculous and unworthy of complicating our elegant text-processing and display capabilities.
• The functions keymap-set, keymap-global-set, keymap-local-set, keymap-substitute, keymap-lookup, and some others were deleted. We have found the traditional define-key, global-set-key, local-set-key, substitute-key-definition, and key-binding more than enough, and their minor inconsistencies in the syntax of keys they accept a source of endless fun in Emacs Lisp programming. Why make Emacs programming a dull place? For the same reasons we deleted key-valid-p, since we consider the permissive nature of kbd more in the spirit of Emacs Lisp.
• Yanking of anything but plain text from other applications becomes more and more an unnecessary feature as you move back in time, so we dropped support for pasting media like HTML and images via the clipboard. If you really need to yank those into an Emacs buffer, you can go via a disk file.
• We removed unnecessary functions string-pixel-width and string-glyph-split, as we consider it inappropriate for Lisp programs to do display layout calculations, where these functions come in handy. Display is for the display engine, written in C, and should stay there!
• Various new Xwidget functions, such as xwidget-perform-lispy-event, xwidget-webkit-load-html, and xwidget-webkit-back-forward-list, were deleted as part of our continuing effort to gradually delete the entire Xwidget functionality in some previous release of Emacs.
• Setting the :stderr property of a process in a make-process call once again forces the process’s connection to use pipes, not ptys, for all the standard streams — a considerable simplification of this complex interface.
• To keep the amount of Lisp functions from growing out of control, we deleted string-equal-ignore-case. Use compare-strings instead.

  Several features that complicated the byte compiler have been removed:

  • The warnings about quoting mistakes in documentation strings. You are expected to find such mistakes yourself, by eyeballing the resulting *Help* buffer display.
  • The warnings about malformed defcustom types, like double-quoting symbols in choice lists.
• The macro with-buffer-unmodified-if-unchanged was deleted. Lisp programs that need to leave the buffer unmodified in these cases can always compare the text before and after the modifications.
• The functions string-edit and read-string-from-buffer were removed, as we consider the fun of programming them anew every time an important part of the education of each Emacs Lisp developer.
• We deleted the function readablep and the related variable print-unreadable-function, since no one is supposed to want to print unreadable Lisp objects.
• The facility for storing multisession variables was deleted as an unnecessary complication. With it are gone multisession-value, define-multisession-variable, and list-multisession-values.
• The support for the cursor-face text property was dropped. We consider the rest of the faces adequate for supporting this functionality.
• The function tooltip-show dropped support for optional face arguments text-face and default-face that allow fancy control of the face of the tip text and top frame colors. We decided that tooltips should all look the same, to prevent user confusion.
• As part of the ongoing quest for simplicity, many other functions and variables have been eliminated. Other functions and variables, that were declared obsolete since Emacs 24, have been added back, in preparation for releasing Emacs 24 in some distant past.