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## Appendix A Emacs 24 Antinews

For those users who live backwards in time, here is information about downgrading to Emacs version 24.5. We hope you will enjoy the greater simplicity that results from the absence of many Emacs 25.1 features.

### A.1 Old Lisp Features in Emacs 24

- The requirement that `setq` and `setf` must be called with an even number of arguments has been removed. You can now call them with an odd number of arguments, and Emacs will helpfully supply a `nil` for the missing one. Simplicity rules!
- `M-x shell` and `M-x compile` set the `EMACS` environment variable, as they should, to indicate that the subprocess is run by Emacs. This is so packages that took years to learn how to work around that setting could continue using their code to that effect.
- The `save-excursion` form saves and restores the mark, as expected. No more need for the new `save-mark-and-excursion`, which has been deleted.
- We have removed the `text-quoting-style` variable and the associated functionality that translates quote characters in messages displayed to the user and in help buffers. Emacs now shows exactly the same quote characters as you wrote in your code! Likewise, `substitute-command-keys` leaves the quote characters alone. As you move back in time, Unicode support becomes less and less important, so no need to display those fancy new quotes the Unicode Standard invented.
- Regular expressions have been simplified by removing support for Unicode character properties in regexp classes. As result, `[:alpha:]` and `[:alnum:]` will match any character with a word syntax, and `[:graph:]` and `[:print:]` will match any multibyte character, including surrogates and unassigned codepoints. Once again, this is in line with diminishing importance of Unicode as you move back in time.
- Evaluating ‘`(/ n)`’ will now yield n. We have realized that interpreting that as in Common Lisp was a bad mistake that needed to be corrected.
- The `pcase` form was significantly simplified by removing the UPatterns `quote` and `app`. To further simplify this facility, we’ve removed `pcase-defmacro`, since we found no need for letting Lisp programs define new UPatterns.
- We’ve removed the text properties `cursor-intangible` and `cursor-sensor-functions`, replacing them by the much simpler `intangible`, `point-entered`, and `point-left` properties. The latter are implemented on a much lower level, and therefore are better integrated with user expectations. For similar reasons, `cursor-intangible-mode` and `cursor-sensor-mode` were removed; use the hook variable `inhibit-point-motion-hooks` which is no longer obsolete.
- Process creation and management functions were significantly improved and simplified by removing `make-process` and the `pipe` connection type. Redirecting `stderr` of a subprocess should be done with shell facilities, not by Emacs.
- We decided that shutting up informative messages is bad for user interaction, so we’ve removed the `inhibit-message` variable which could be used to that effect.
- Support for generators and for finalizers has been removed, as we found no real need for these facilities.
- Due to excessive complexity and the diminishing need for Unicode support, the functions `string-collate-lessp` and `string-collate-equalp` were removed. Their locale-independent counterparts `string-lessp` and `string-equal` are so much more simple and yield predictable results that we don’t see any situation where the locale-dependent collation could be useful in Emacs. As result, the `ls-lisp.el` package sorts files in a locale-independent manner.
- In preparation for removal in some past version of Emacs of the bidirectional editing support, we started by deleting two functions `bidi-find-overridden-directionality` and `buffer-substring-with-bidi-context`.
- Time conversion functions, such as `current-time-string`, no longer accept an optional zone argument. If you need to change the current time zone (why?), do that explicitly with `set-time-zone-rule`.
- As part of the ongoing quest for simplicity, many other functions and variables have been eliminated.

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