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Update Antinews in ELisp manual

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* doc/lispref/anti.texi (Antinews): Rewrite for Emacs 27.
* doc/lispref/elisp.texi (Top): Update the top-level menu item for
Antinews.
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Eli Zaretskii 2020-01-11 13:36:07 +02:00
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@ -6,276 +6,184 @@
@c This node must have no pointers.
@node Antinews
@appendix Emacs 25 Antinews
@appendix Emacs 26 Antinews
@c Update the elisp.texi Antinews menu entry with the above version number.
For those users who live backwards in time, here is information about
downgrading to Emacs version 25.3. We hope you will enjoy the greater
downgrading to Emacs version 26.3. We hope you will enjoy the greater
simplicity that results from the absence of many @w{Emacs
@value{EMACSVER}} features.
@section Old Lisp Features in Emacs 25
@itemize @bullet
@item
The concurrency features have been removed. Even in its limited
``mostly cooperative'' form, with only one Lisp thread running at any
given time, it made Emacs significantly more complex for Lisp programs
that need to work correctly in the presence of additional threads.
Lisp objects are again implemented on the C level as integer types,
not as pointers. This might be a small step for Emacs Lisp users, but
it's a giant leap for the Emacs developers who work on the C level,
since it is now again easy to print Lisp object in the debugger in the
decimal format, which is so much easier for debugging. It also makes
calling Emacs functions from the debugger easier, and allows us to
freely mix integers and Lisp objects in the C code.
@item
Handling of file attributes has been simplified by discarding the
accessor functions, such as @code{file-attribute-type} and
@code{file-attribute-modification-time}. Real Lisp programmers always
access the individual attributes by their ordinal numbers, and can
recite those numbers in their sleep.
The test suite was removed from the distribution tarball. We believe
that tests need seldom if ever be run, certainly not by the end
users. Removing the tests from the tarball makes it much smaller,
which is important since disk space becomes more and more at premium
as you move back in time.
@item
The networking code is back at its pristine simplicity, as we deleted
the use of asynchronous DNS resolution, connection, and TLS
negotiation for TLS streams. You no longer need to consider the
resulting complexity and interesting race conditions when you write
Lisp programs that use network communications. As a direct
consequence, the @code{:complete-negotiation} parameter of
@code{gnutls-boot} has become unnecessary, and was removed---just one
example of how removal of asynchronicity simplifies Emacs.
Dynamic module support is disabled by default. This both makes Emacs
smaller (a worthy goal by itself), and removes the complications and
additional complexity related with installing module support files and
letting random shared objects an opportunity to be loaded into Emacs
and mess with it.
@item
We've removed the @file{puny.el} library, so Web sites with
non-@acronym{ASCII} URLs are no longer easily accessible. But such
sites become more and more rare as you move back in time, so having a
specialized library for their support was deemed an unnecessary
maintenance burden.
You now must activate any installed packages only after loading your
init files. That requires an explicit call to
@code{package-initialize} in your init file, which is a Good Thing, as
it makes you think seriously where and indeed whether you'd like your
packages to become available to your sessions. Simplicity should
tramp convenience!
@item
The time conversion functions @code{current-time-string},
@code{current-time-zone}, @code{decode-time},
@code{format-time-string}, and @code{set-time-zone-rule} no longer
accept integer offsets as time zone rules, to make it more of a
challenge to convert foreign timestamps. Also,
@code{format-time-string} no longer converts @samp{%q} to the calendar
quarter, as that is something you can easily do for yourself.
To reduce the amount of code in Emacs related to unimportant features,
we've removed native rotation and resizing of images. You will have
to build Emacs with ImageMagick if you want to resize or rotate images
inside Emacs. We don't expect anyone to miss that.
@item
Field numbers like @samp{%2$} in format specifiers are no longer
available. We decided that their use makes code reading and
comprehension much harder, and that having them is unjustified in the
past where similar features in popular C libraries will also be gone.
We've re-enabled color fonts usage by the XFT font back-end. We
consider the availability of these fonts more important than a random
crash here and there, especially since the use of these fonts for
displaying Emoji will become less and less important as w travel back
in time, and will completely disappear in some past Emacs version.
@item
Since the built-in capability to display line numbers has been removed
(@pxref{Antinews,,, emacs, The GNU Emacs Manual}), we've also deleted
the @code{line-number-display-width} function and the support for the
@code{display-line-numbers-disable} property, as Lisp programs that do
their own display layout decisions no longer need to cater to this
tricky feature.
The function @code{network-interface-list} can now return only IPv4
addresses. We consider the complexity introduced by IPv6 to be too
much to be justified, and on the other hand its removal is the step in
the right direction, given that IPv6 is expected to be completely
removed as we move back in time.
@item
Regular expressions have been simplified by removing support for
Unicode character properties in the @code{[:blank:]} regexp class. As
result, this class will match only spaces and tabs. Once again, this
is in line with diminishing importance of Unicode as you move back in
time.
The limit on repetitions in regular expressions was reduced to
@ifnottex
2**15 @minus{} 1.
@end ifnottex
@tex
@math{2^{15}-1}.
@end tex
We envision that regular expressions will become more and more simple
as we move towards the distant past.
@item
For similar reasons, we removed the function @code{char-from-name}.
It should be easy enough to access the full list of Unicode characters
returned by @code{ucs-names} instead, for as long as Unicode support
in Emacs exists (which shouldn't be too long).
To simplify code and reduce complexity, we removed the capability of
searching programs on remote hosts in @code{executable-find}. If you
really need this feature (why would you?), you can always write your
own shell script and run it on the remote.
@item
Various functions that accept file names as arguments, such as
@code{file-attributes}, @code{file-symlink-p}, and
@code{make-symbolic-link} gained back the special support for file
names quoted with @samp{/:}, and they now interpret @samp{~} in
symlink targets as you'd expect: to mean your home directory. The
confusing differences between the operation of these functions in
interactive and non-interactive invocations has been removed.
The @code{:extend} face attribute is no longer available; all faces
have their background color extended by default past end of line.
This should significantly simplify face management and remove
unnecessary code bloat, as well as make faces significantly simpler to
understand and use.
@item
Several functions that create or rename their files now treat their
destination specially if it happens to be a directory, even when its
name does not appear to be that of a directory. For example,
@code{(rename-file "A" "B")} no longer renames @file{A} to @file{B} if
@file{B} happens to be a directory. This is so that dealing with
files becomes more of an adventure.
The predicates @code{display-blink-cursor-p} and
@code{display-symbol-keys-p} were deleted. They are rarely if ever
needed, and can easily be substituted by appropriate calls to old and
proven APIs like @code{display-graphic-p}. As an additional bonus,
writing Lisp programs that depend on this functionality will make sure
the programmer understands better what exactly is the required
features of the display terminal.
@item
The @code{format} function now returns new strings in more cases, to
place more stress on the Emacs memory manager and thereby test Emacs
better.
Relative directories in the value of the @env{HOME} environment
variable are once again interpreted relative to the
@code{default-directory} of the current buffer. This is much simpler,
and also allows @env{HOME} to resolve to a different place in
different buffers, which allows some interesting applications.
For the same reasons, @code{file-name-absolute-p} now again considers
@file{~foo} an absolute file name, even if there's no known user
@samp{foo}. This means a Lisp program which uses such file names will
always work the same on any system, regardless of its known users.
@item
The function @file{assoc} has been simplified by removing its third
optional argument. It now always uses @code{equal} for comparison.
Likewise, @code{alist-get} always uses @code{assq}, and @code{map-get}
and @code{map-put} always use @code{eql} for their comparisons.
File-related primitives like @code{file-attributes},
@code{file-modes}, @code{file-newer-than-file-p}, and some others once
again return @code{nil} when the underlying low-level APIs fail,
instead of signaling an error. We decided that functions which signal
errors require more complex code from Lisp programs which use them,
and found this complexity unjustified when returning @code{nil} will
do.
@item
Numeric comparisons and the functions @code{format},
@code{make-hash-table}, @code{min}, @code{max} and @code{logb} now
occasionally round values internally to make their results less
predictable.
Similarly, old-style backquotes no longer signal errors; they generate
warnings instead. You can remove error handling from programs that
use backquotes.
@item
The functions @code{ffloor}, @code{fceiling}l, @code{ftruncate} and
@code{fround} now accept integer arguments. Conversely, functions
like @code{decode-char} that accept floating-point integers now accept
arguments that are not integers. In both cases the results are
amusingly nonsensical sometimes.
Formatting floating-point numbers has been sped up by letting the
underlying implementation produce unpredictable values, instead of
signaling errors when the number is too large to format correctly. We
believe the Emacs Lisp programmers should always know what they are
doing when they deal with floating-point values.
@item
GnuTLS cryptographic functions are no longer available in Emacs. We
have decided that the needs for such functionality are deteriorating,
and their cumbersome interfaces make them hard to use.
The function @code{read-char-from-minibuffer} was deleted. We decided
that @code{read-char} should be enough for any Lisp program that needs
to ask the user for a single-character input, in recognition of the
fact that nothing makes Emacs Lisp hackers rejoice more than the need
to sit down and write yet another interactive question-and-answer
function, and make it optimal for each specific case. Consequently,
no history is provided for such responses (why would someone want
history of single-key strokes, anyway?).
@item
We have removed support for records of user-defined types, and
@code{cl-defstruct} no longer uses records. This removes the
potential for quite a few places where existing and past code could be
broken by records.
The function @code{ngettext} was deleted. Non-English languages will
become less and less widespread, let alone useful, as you move back in
time, so we took this small step in that direction, and simplified
Emacs as a nice bonus.
@item
You can again use @code{string-as-unibyte},
@code{string-make-multibyte}, and other similar functions, without
being annoyed by messages about their deprecation. This is in
preparation for removal of multibyte text from Emacs in the distant
past.
Focus-change notifications on text-mode frames are no longer
recognized or supported. You can now safely disregard the possibility
of receiving such notifications on TTY frames. This is one small step
on the long road of removing all non-character input events Emacs
supports on TTY frames.
@item
The @code{string-version-lessp} function has been removed, to
encourage programmers to use their own idiosyncratic methods to
determine whether one version string precedes another.
Face specifications in @code{face-remapping-alist} now have to be
buffer-specific, without any differences between windows showing the
same buffers. This allowed us to remove a lot of unneeded code bloat
from Emacs, and make the face handling much simpler.
@item
The function @code{read-color} no longer displays color names using
each color as the background. We have determined that this surprises
users and produces funny inconsistent results on color-challenged
terminals.
The @samp{%o} and @samp{%x} formats now always produce unsigned
values, as you'd expect. This allows you to reveal the underlying
machine representation, which is different on each architecture,
something we consider a valuable feature.
@item
Support for 24-bit color on text terminals has been dropped, since
it wasn't needed long ago.
We no longer highlight in @code{font-lock-warning-face} symbols with
confusable quote characters, such as U+2018. Detecting them
needed non-trivial amount of code, and we firmly believe that Lisp
programmers always know what they are doing, and don't need to be
annoyed with typefaces that stand out and distract.
@item
We removed the function @code{file-name-case-insensitive-p}, as
testing for the OS symbol should be enough for the observable past to
come, and learning to use yet another API is a burden.
The function @code{file-system-info} was dropped on Posix platforms,
since you can always invoke @command{df} instead and parse its
output.
@item
The function @code{read-multiple-choice} is also gone, in recognition
of the fact that nothing makes Emacs Lisp hackers rejoice more than
the need to sit down and write yet another interactive
question-and-answer function, and make it optimal for each specific
case.
@item
The function @code{add-variable-watcher} and the corresponding
debugger command @code{debug-on-variable-change} have been removed.
They make debugging more complicated, while examining the value of a
variable at each stop point is easy enough to cover the same use
cases. Let simplicity rule!
@item
The function @code{mapcan} is gone; use @code{mapcar} instead, and
process the resulting list as you see fit.
@item
Low-level list functions like @code{length} and @code{member} can now
loop indefinitely when given cyclic lists, causing Emacs to freeze.
This can help these functions run a tiny bit faster in the usual case
where the input is not cyclic.
@item
The @code{write-region} function no longer propagates its
@var{lockname} argument to file name handlers.
@item
You can once again write a Lisp program that returns funny random
values from @code{file-attributes} by having another process alter the
filesystem while Emacs is accessing the file. This can give rise to
some interesting applications in the near past.
@item
The functions @code{file-attributes}, @code{file-symlink-p}, and
@code{make-symbolic-link} now quietly mutate the target of a local
symbolic link in some cases, to make it more of a challenge to deal
with arbitrary symlinks in Emacs code.
@item
The error @code{file-missing} has been removed; operations now lump
such errors into the @code{file-error} category instead.
@item
The function @code{delete-directory} now signals an error if operating
recursively and some other process deletes the directory before this
function gets to it.
@item
The @code{dutch} input method now attempts to support Turkish too,
albeit incorrectly. Also, it converts @samp{IJ} and @samp{ij} to
special characters instead of leaving them alone.
@item
Non-breaking hyphens and approximations to quotes are now displayed
just with the @code{escape-glyph} face instead of having faces of
their own. This is simpler and gives the user amusing puzzles to
solve when viewing text containing these characters.
@item
The user option @code{electric-quote-context-sensitive} and the
variable @code{electric-quote-inhibit-functions}, so that electric
quoting is simpler and more likely to do the wrong thing.
@item
The user option @code{text-quoting-style} has been removed, and is now
just a variable.
@item
We have removed the functions @code{file-name-quote},
@code{file-name-unquote}, and @code{file-name-quoted-p}. Writing code
that checks whether a file name is already quoted is easy, and doubly
quoting a file name should not produce any problems for well-written
Lisp code.
@item
Frame parameters like @code{z-group}, @code{min-width},
@code{parent-frame}, @code{delete-before}, etc. have been removed.
Emacs should not replace your window-manager, certainly not as
window-managers become less and less capable.
@item
We decided that the format of mode line and header line should be
customizable only based on buffers; the @code{mode-line-format} and
@code{header-line-format} window parameters have been removed.
@item
Emacs now normally builds a limited @command{movemail} substitute that
retrieves POP3 email only via insecure channels, and the
configure-time option @option{--with-mailutils} has been removed.
This simplifies Emacs setup when security is not important.
@item
The configure-time option @option{--enable-gcc-warnings=warn-only}
has been removed, so that build-time warnings are always fatal now.
@item
The configure-time option @option{--disable-build-details} has been
removed. This way, Emacs builds are unique and irreproducible.
@item
The variable @code{emacs-version} now includes the build number
instead of storing it separately in @code{emacs-build-number}.
@item
Emacs has been ported to IRIX.
@item
Several options and variables have been removed to simplify Emacs and
potentially make it less reliable. These include the
@option{--module-assertions} option, the
@code{attempt-stack-overflow-recovery} variable, and the
@code{attempt-orderly-shutdown-on-fatal-signal} variable.
The functions that implement the @samp{base64url} encoding were
removed, as they can always be emulated by suitable tweaking of the
normal base-64 encoding. No need to bloat Emacs and force Lisp
programmers learn more interfaces on this account.
@item
As part of the ongoing quest for simplicity, many other functions and

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@ -233,7 +233,7 @@ To view this manual in other formats, click
Appendices
* Antinews:: Info for users downgrading to Emacs 25.
* Antinews:: Info for users downgrading to Emacs 26.
* GNU Free Documentation License:: The license for this documentation.
* GPL:: Conditions for copying and changing GNU Emacs.
* Tips:: Advice and coding conventions for Emacs Lisp.