184 lines
6.7 KiB
Text
184 lines
6.7 KiB
Text
@c -*-texinfo-*-
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@c This is part of the GNU Emacs Lisp Reference Manual.
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@c Copyright (C) 1999, 2002--2023 Free Software Foundation, Inc.
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@c See the file elisp.texi for copying conditions.
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@c This node must have no pointers.
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@node Antinews
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@appendix Emacs 27 Antinews
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@c Update the elisp.texi Antinews menu entry with the above version number.
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For those users who live backwards in time, here is information about
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downgrading to Emacs version 27.2. We hope you will enjoy the greater
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simplicity that results from the absence of many @w{Emacs
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@value{EMACSVER}} features.
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@itemize @bullet
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@item
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The annoying @code{lexical-binding} local variable now heeds the
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value of @code{enable-local-variables}: if it's @code{nil}, the
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@code{lexical-binding} cookie is ignored. We are working hard on
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removing the lexical-binding support in some past Emacs version, and
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this small step advances us back to that change.
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@item
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The @code{load-dangerous-libraries} variable is not obsolete, as it
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must be used to allow loading Lisp compiled by XEmacs, which will
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become more and more important as you move back in time.
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@item
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The optional @var{modes} argument of @code{interactive} is not
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supported, and every command is deemed applicable to any major mode.
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We believe this makes the life of Lisp programmers much simpler, as
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there's now no need to tag commands with the modes where they make
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sense.
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@item
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Shorthands for Lisp symbols have been removed, which makes loading
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Lisp files and handling Lisp symbols much simpler and more efficient.
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This is important for decent performance on slower CPUs as you move
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back in time.
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@item
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To reduce the amount of code in Emacs related to unimportant features,
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we've removed the variables @code{global-minor-modes} and
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@code{local-minor-modes}. If your Lisp program needs to determine
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whether some minor mode is in effect, it will have to test explicitly
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for every mode. We don't expect anyone to miss those fancy variables.
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@item
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The default preference for servicing sub-processes that produce output
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at a high rate, and the associated variable
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@code{process-prioritize-lower-fds}, have been removed. Moving back
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in time means fewer and fewer programs can produce such high-rate
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output, so this features becomes just useless crud.
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@item
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The encodings that are variants of EBCDIC were removed. This includes
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@code{ibm256}, @code{ibm273}, and others---variants of the EBCDIC
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encoding tailored for some Japanese and European locales. You won't
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need those where you are going.
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@item
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The ``Bindat type expression'' description language has been removed,
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as the existing data layout specifications are perfectly suited for
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this job.
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@item
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To simplify code and reduce complexity, we removed the capability of
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specifying the success handler in @code{condition-case} via the
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@code{:success} keyword. If you really need this feature (why would
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you?), you can always write some simple Lisp that has the same effect.
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@item
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Emacs modules can no longer provide interactive functions, or install
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finalizers, nor open channels to existing pipe sub-processes. All
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this is extra ballast, especially since we plan on removing modules in
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some past Emacs version. The @code{make_unibyte_string} module API
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was removed for the same reason.
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@item
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To keep Emacs clean and elegant, we've removed the
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@code{print-integers-as-characters} option. Recognizing characters by
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their decimal codes is a basic requirement for Emacs Lisp programmers,
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and with the expected decrease in use of Unicode characters, this will
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be soon limited to ASCII only: surely something you all can master!
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@item
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The optional @var{count} argument of the @code{directory-files}
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function has been removed. Extracting the first @var{n} members from
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the full list is trivial, so this is a significant simplification for
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an insignificant cost.
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@item
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Functions that create sub-processes and network connections no longer
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accept the @code{:coding} argument; use
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@code{set-process-coding-system} or bind
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@code{coding-system-for-read/write} instead: again, a significant
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reduction in Emacs complexity for little or no cost.
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@item
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We deleted from the macros @code{define-derived-mode} and
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@code{define-minor-mode} the code which allowed using the
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@code{:interactive} argument. The possibility of marking a mode
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non-interactive makes very little sense,
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@item
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The possibility of having links to man pages in doc strings has been
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removed. Use plain text instead, if you need such references.
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@item
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Temporary buffers are no longer exempt from running any buffer-related
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hooks. Programs that don't want such hooks in some buffer can always
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disable it locally, whereas making that simpler complicates Emacs for
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no good reason.
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@item
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Several features that complicated the byte compiler have been removed:
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@itemize @minus
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@item
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The checks for missing declarations of dynamic variables. This will
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continue making less and less sense as we move away of lexical-binding
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support.
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@item
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The ability of compiling symlinked @file{*.el} files, which is really
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gross: copy the files instead.
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@item
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The warnings about too-wide doc strings---that is just a nuisance, as
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the programmers should be trusted to know what they are doing.
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@end itemize
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@item
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We deleted several features of the @code{pcase} macro, in accordance
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with our general plan to remove @code{pcase} from Emacs:
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@itemize @minus
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@item
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The @code{cl-type} pattern.
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@item
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the @code{pcase-setq} macro.
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@item
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The @code{pcase-compile-patterns} function.
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@end itemize
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@item
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Some of the keywords used in Edebug specification lists were deemed to
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be of little use, and were therefore removed: @code{&interpose},
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@code{&error}, and @code{&name}. The long-term plane is for Emacs to
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drop Edebug entirely, leaving only the trusted Lisp debugger, and we
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continue working according to that plan.
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@item
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The function @code{object-intervals} was dropped, as a Lisp program
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can easily collect the intervals of a buffer or a string by iterating
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through them one by one.
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@item
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We decided that the @code{require-theme} function is an unnecessary
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complication, so we deleted it. Lisp programs can easily search along
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@code{custom-theme-load-path} instead.
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@item
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The convenience functions @code{length<}, @code{length>}, and
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@code{length=} were removed, as using @code{length} followed by a
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comparison should be good enough for everyone, especially considering
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that the typical length of a list keeps going down as you move back
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through time.
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@item
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The variable @code{current-minibuffer-command} is no longer available,
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as we found little justification for keeping it.
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@item
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As part of the ongoing quest for simplicity, many other functions and
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variables have been eliminated. Other functions and variables, that
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were declared obsolete since Emacs 23, have been added back, in
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preparation for releasing Emacs 23 in some distant past.
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@end itemize
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