elisp: Antinews
Appendix A Emacs 24 Antinews
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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 25.3 features.
A.1 Old Lisp Features in Emacs 24
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• 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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