(elide-head): Change error to message.

[emacs.git] / etc / ONEWS.2

GNU Emacs NEWS -- history of user-visible changes.  26-Mar-1986
Copyright (C) 1986 Richard M. Stallman.
See the end for copying conditions.

For older news, see the file ONEWS.1.
\f
Changes in Emacs 17

* Frustrated?

Try M-x doctor.

* Bored?

Try M-x hanoi.

* Brain-damaged?

Try M-x yow.

* Sun3, Tahoe, Apollo, HP9000s300, Celerity, NCR Tower 32,
  Sequent, Stride, Encore, Plexus and AT&T 7300 machines supported.

The Tahoe, Sun3, Sequent and Celerity use 4.2.  In regard to the
Apollo, see the file APOLLO in this directory.  NCR Tower32,
HP9000s300, Stride and Nu run forms of System V.  System V rel 2 also
works on Vaxes now.  See etc/MACHINES.

* System V Unix supported, including subprocesses.

It should be possible now to bring up Emacs on a machine running
mere unameliorated system V Unix with no major work; just possible bug
fixes.  But you can expect to find a handful of those on any machine
that Emacs has not been run on before.

* Berkeley 4.1 Unix supported.

See etc/MACHINES.

* Portable `alloca' provided.

Emacs can now run on machines that do not and cannot support the library
subroutine `alloca' in the canonical fashion, using an `alloca' emulation
written in C.

* On-line manual.

Info now contains an Emacs manual, with essentially the same text
as in the printed manual.

The manual can now be printed with a standard TeX.

Nicely typeset and printed copies of the manual are available
from the Free Software Foundation.

* Backup file version numbers.

Emacs now supports version numbers in backup files.

The first time you save a particular file in one editing session,
the old file is copied or renamed to serve as a backup file.
In the past, the name for the backup file was made by appending `~'
to the end of the original file name.

Now the backup file name can instead be made by appending ".~NN~" to
the original file name, where NN stands for a numeric version.  Each
time this is done, the new version number is one higher than the
highest previously used.

Thus, the active, current file does not have a version number.
Only the backups have them.

This feature is controlled by the variable `version-control'.  If it
is `nil', as normally, then numbered backups are made only for files
that already have numbered backups.  Backup names with just `~' are
used for files that have no numbered backups.

If `version-control' is `never', then the backup file's name is
made with just `~' in any case.

If `version-control' is not `nil' or `never', numbered backups are
made unconditionally.

To prevent unlimited consumption of disk space, Emacs can delete
old backup versions automatically.  Generally Emacs keeps the first
few backups and the latest few backups, deleting any in between.
This happens every time a new backup is made.  The two variables that
control the deletion are `kept-old-versions' and `kept-new-versions'.
Their values are, respectively, the number of oldest backups to keep
and the number of newest ones to keep, each time a new backup is made.
The value of `kept-new-versions' includes the backup just created.
By default, both values are 2.

If `trim-versions-without-asking' is non-`nil', the excess middle versions
are deleted without a murmur.  If it is `nil', the default, then you
are asked whether the excess middle versions should really be deleted.

Dired has a new command `.' which marks for deletion all but the latest
and oldest few of every numeric series of backups.  `kept-old-versions'
controls the number of oldest versions to keep, and `dired-kept-versions'
controls the number of latest versions to keep.  A numeric argument to
the `.' command, if positive, specifies the number of latest versions
to keep, overriding `dired-kept-versions'.  A negative argument specifies
the number of oldest versions to keep, using minus the argument to override
`kept-old-versions'.

* Immediate conflict detection.

Emacs now locks the files it is modifying, so that if
you start to modify within Emacs a file that is being
modified in another Emacs, you get an immediate warning.

The warning gives you three choices:
1. Give up, and do not make any changes.
2. Make changes anyway at your own risk.
3. Make changes anyway, and record yourself as
 the person locking the file (instead of whoever
 was previously recorded.)

Just visiting a file does not lock it.  It is locked
when you try to change the buffer that is visiting the file.
Saving the file unlocks it until you make another change.

Locking is done by writing a lock file in a special designated
directory.  If such a directory is not provided and told to
Emacs as part of configuring it for your machine, the lock feature
is turned off.

* M-x recover-file.

This command is used to get a file back from an auto-save
(after a system crash, for example).  It takes a file name
as argument and visits that file, but gets the data from the
file's last auto save rather than from the file itself.

* M-x normal-mode.

This command resets the current buffer's major mode and local
variables to be as specified by the visit filename, the -*- line
and/or the Local Variables: block at the end of the buffer.
It is the same thing normally done when a file is first visited.

* Echo area messages disappear shortly if minibuffer is in use.

Any message in the echo area disappears after 2 seconds
if the minibuffer is active.  This allows the minibuffer
to become visible again.

* C-z on System V runs a subshell.

On systems which do not allow programs to be suspended, the C-z command
forks a subshell that talks directly to the terminal, and then waits
for the subshell to exit.  This gets almost the effect of suspending
in that you can run other programs and then return to Emacs.  However,
you cannot log out from the subshell.

* C-c is always a prefix character.

Also, subcommands of C-c which are letters are always
reserved for the user.  No standard Emacs major mode
defines any of them.

* Picture mode C-c commands changed.

The old C-c k command is now C-c C-w.
The old C-c y command is now C-c C-x.

* Shell mode commands changed.

All the special commands of Shell mode are now moved onto
the C-c prefix.  Most are not changed aside from that.
Thus, the old Shell mode C-c command (kill current job)
is now C-c C-c; the old C-z (suspend current job) is now C-c C-z,
etc.

The old C-x commands are now C-c commands.  C-x C-k (kill output)
is now C-c C-o, and C-x C-v (show output) is now C-c C-r.

The old M-= (copy previous input) command is now C-c C-y.

* Shell mode recognizes aliases for `pushd', `popd' and `cd'.

Shell mode now uses the variable `shell-pushd-regexp' as a
regular expression to recognize any command name that is
equivalent to a `pushd' command.  By default it is set up
to recognize just `pushd' itself.  If you use aliases for
`pushd', change the regexp to recognize them as well.

There are also `shell-popd-regexp' to recognize commands
with the effect of a `popd', and `shell-cd-regexp' to recognize
commands with the effect of a `cd'.

* "Exit" command in certain modes now C-c C-c.

These include electric buffer menu mode, electric command history
mode, Info node edit mode, and Rmail edit mode.  In all these
modes, the command to exit used to be just C-c.

* Outline mode changes.

Lines that are not heading lines are now called "body" lines.
The command `hide-text' is renamed to `hide-body'.
The key M-H is renamed to C-c C-h.
The key M-S is renamed to C-c C-s.
The key M-s is renamed to C-c C-i.

Changes of line visibility are no longer undoable.  As a result,
they no longer use up undo memory and no longer interfere with
undoing earlier commands.

* Rmail changes.

The s and q commands now both expunge deleted messages before saving;
use C-x C-s to save without expunging.

The u command now undeletes the current message if it is deleted;
otherwise, it backs up as far as necessary to reach a deleted message,
and undeletes that one.  The u command in the summary behaves likewise,
but considers only messages listed in the summary.  The M-u command
has been eliminated.

The o and C-o keys' meanings are interchanged.
o now outputs to an Rmail file, and C-o to a Unix mail file.

The F command (rmail-find) is renamed to M-s (rmail-search).
Various new commands and features exist; see the Emacs manual.

* Local bindings described first in describe-bindings.

* [...], {...} now balance in Fundamental mode.

* Nroff mode and TeX mode.

The are two new major modes for editing nroff input and TeX input.
See the Emacs manual for full information.

* New C indentation style variable `c-brace-imaginary-offset'.

The value of `c-brace-imaginary-offset', normally zero, controls the
indentation of a statement inside a brace-group where the open-brace
is not the first thing on a line.  The value says where the open-brace
is imagined to be, relative to the first nonblank character on the line.

* Dired improvements.

Dired now normally keeps the cursor at the beginning of the file name,
not at the beginning of the line.  The most used motion commands are
redefined in Dired to position the cursor this way.

`n' and `p' are now equivalent in dired to `C-n' and `C-p'.

If any files to be deleted cannot be deleted, their names are
printed in an error message.

If the `v' command is invoked on a file which is a directory,
dired is run on that directory.

* `visit-tag-table' renamed `visit-tags-table'.

This is so apropos of `tags' finds everything you need to
know about in connection with Tags.

* `mh-e' library uses C-c as prefix.

All the special commands of `mh-rmail' now are placed on a
C-c prefix rather than on the C-x prefix.  This is for
consistency with other special modes with their own commands.

* M-$ or `spell-word' checks word before point.

It used to check the word after point.

* Quitting during autoloading no longer causes trouble.

Now, when a file is autoloaded, all function redefinitions
and `provide' calls are recorded and are undone if you quit
before the file is finished loading.

As a result, it no longer happens that some of the entry points
which are normally autoloading have been defined already, but the
entire file is not really present to support them.

* `else' can now be indented correctly in C mode.

TAB in C mode now knows which `if' statement an `else' matches
up with, and can indent the `else' correctly under the `if',
even if the `if' contained such things as another `if' statement,
or a `while' or `for' statement, with no braces around it.

* `batch-byte-compile'

Runs byte-compile-file on the files specified on the command line.
All the rest of the command line arguments are taken as files to
compile (or, if directories, to do byte-recompile-directory on).
Must be used only with -batch, and kills emacs on completion.
Each file will be processed even if an error occurred previously.
For example, invoke `emacs -batch -f batch-byte-compile *.el'.

* `-batch' changes.

`-batch' now implies `-q': no init file is loaded by Emacs when
`-batch' is used.  Also, no `term/TERMTYPE.el' file is loaded.  Auto
saving is not done except in buffers in which it is explicitly
requested.  Also, many echo-area printouts describing what is going on
are inhibited in batch mode, so that the only output you get is the
output you program specifically.

One echo-area message that is not suppressed is the one that says
that a file is being loaded.  That is because you can prevent this
message by passing `t' as the third argument to `load'.

* Display of search string in incremental search.

Now, when you type C-s or C-r to reuse the previous search
string, that search string is displayed immediately in the echo area.

Three dots are displayed after the search string while search
is actually going on.

* View commands.

The commands C-x ], C-x [, C-x /, C-x j and C-x o are now
available inside `view-buffer' and `view-file', with their
normal meanings.

* Full-width windows preferred.

The ``other-window'' commands prefer other full width windows,
and will split only full width windows.

* M-x rename-file can copy if necessary.

When used between different file systems, since actual renaming does
not work, the old file will be copied and deleted.

* Within C-x ESC, you can pick the command to repeat.

While editing a previous command to be repeated, inside C-x ESC,
you can now use the commands M-p and M-n to pick an earlier or
later command to repeat.  M-n picks the next earlier command
and M-p picks the next later one.  The new command appears in
the minibuffer, and you can go ahead and edit it, and repeat it
when you exit the minibuffer.

Using M-n or M-p within C-x ESC is like having used a different
numeric argument when you ran C-x ESC in the first place.

The command you finally execute using C-x ESC is added to the
front of the command history, unless it is identical with the
first thing in the command history.

* Use C-c C-c to exit from editing within Info.

It used to be C-z for this.  Somehow this use of C-z was
left out when all the others were moved.  The intention is that
C-z should always suspend Emacs.

* Default arg to C-x < and C-x > now window width minus 2.

These commands, which scroll the current window horizontally
by a specified number of columns, now scroll a considerable
distance rather than a single column if used with no argument.

* Auto Save Files Deleted.

The default value of `delete-auto-save-files' is now `t', so that
when you save a file for real, its auto save file is deleted.

* Rnews changes.

The N, P and J keys in Rnews are renamed to M-n, M-p and M-j.
These keys move among newsgroups.

The n and p keys for moving sequentially between news articles now
accept repeat count arguments, and the + and - keys, made redundant by
this change, are eliminated.

The s command for outputting the current article to a file
is renamed as o, to be compatible with Rmail.

* Sendmail changes.

If you have a ~/.mailrc file, Emacs searches it for mailing address
aliases, and these aliases are expanded when you send mail in Emacs.

Fcc fields can now be used in the headers in the *mail* buffer
to specify files in which copies of the message should be put.
The message is written into those files in Unix mail file format.
The message as sent does not contain any Fcc fields in its header.
You can use any number of Fcc fields, but only one file name in each one.
The variable `mail-archive-file-name', if non-`nil', can be a string
which is a file name; an Fcc to that file will be inserted in every
message when you begin to compose it.

A new command C-c q now exists in Mail mode.  It fills the
paragraphs of an old message that had been inserted with C-c y.

When the *mail* buffer is put in Mail mode, text-mode-hook
is now run in addition to mail-mode-hook.  text-mode-hook
is run first.

The new variable `mail-header-separator' now specifies the string
to use on the line that goes between the headers and the message text.
By default it is still "--text follows this line--".

* Command history truncated automatically.

Just before each garbage collection, all but the last 30 elements
of the command history are discarded.
\f
Incompatible Lisp Programming Changes in Emacs 17

* `&quote' no longer supported.

This feature, which allowed Lisp functions to take arguments
that were not evaluated, has been eliminated, because it is
inescapably hard to make the compiler work properly with such
functions.

You should use macros instead.  A simple way to change any
code that uses `&quote' is to replace

   (defun foo (&quote x y z) ...

with

   (defmacro foo (x y z)
     (list 'foo-1 (list 'quote x) (list 'quote y) (list 'quote z)))

   (defun foo-1 (x y z) ...

* Functions `region-to-string' and `region-around-match' removed.

These functions were made for compatibility with Gosling Emacs, but it
turns out to be undesirable to use them in GNU Emacs because they use
the mark.  They have been eliminated from Emacs proper, but are
present in mlsupport.el for the sake of converted mocklisp programs.

If you were using `region-to-string', you should instead use
`buffer-substring'; then you can pass the bounds as arguments and
can avoid setting the mark.

If you were using `region-around-match', you can use instead
the two functions `match-beginning' and `match-end'.  These give
you one bound at a time, as a numeric value, without changing
point or the mark.

* Function `function-type' removed.

This just appeared not to be very useful.  It can easily be written in
Lisp if you happen to want it.  Just use `symbol-function' to get the
function definition of a symbol, and look at its data type or its car
if it is a list.

* Variable `buffer-number' removed.

You can still use the function `buffer-number' to find out
a buffer's unique number (assigned in order of creation).

* Variable `executing-macro' renamed `executing-kbd-macro'.

This variable is the currently executing keyboard macro, as
a string, or `nil' when no keyboard macro is being executed.

* Loading term/$TERM.

The library term/$TERM (where $TERM get replaced by your terminal
type), which is done by Emacs automatically when it starts up, now
happens after the user's .emacs file is loaded.

In previous versions of Emacs, these files had names of the form
term-$TERM; thus, for example, term-vt100.el, but now they live
in a special subdirectory named term, and have names like
term/vt100.el.

* `command-history' format changed.

The elements of this list are now Lisp expressions which can
be evaluated directly to repeat a command.

* Unused editing commands removed.

The functions `forward-to-word', `backward-to-word',
`upcase-char', `mark-beginning-of-buffer' and `mark-end-of-buffer'
have been removed.  Their definitions can be found in file
lisp/unused.el if you need them.
\f
Upward Compatible Lisp Programming Changes in Emacs 17

* You can now continue after errors and quits.

When the debugger is entered because of a C-g, due to
a non-`nil' value of `debug-on-quit', the `c' command in the debugger
resumes execution of the code that was running when the quit happened.
Use the `q' command to go ahead and quit.

The same applies to some kinds of errors, but not all.  Errors
signaled with the Lisp function `signal' can be continued; the `c'
command causes `signal' to return.  The `r' command causes `signal' to
return the value you specify.  The `c' command is equivalent to `r'
with the value `nil'.

For a `wrong-type-argument' error, the value returned with the `r'
command is used in place of the invalid argument.  If this new value
is not valid, another error occurs.

Errors signaled with the function `error' cannot be continued.
If you try to continue, the error just happens again.

* `dot' renamed `point'.

The word `dot' has been replaced with `point' in all
function and variable names, including:

  point, point-min, point-max,
  point-marker, point-min-marker, point-max-marker,
  window-point, set-window-point,
  point-to-register, register-to-point,
  exchange-point-and-mark.

The old names are still supported, for now.

* `string-match' records position of end of match.

After a successful call to `string-match', `(match-end 0)' will
return the index in the string of the first character after the match.
Also, `match-begin' and `match-end' with nonzero arguments can be
used to find the indices of beginnings and ends of substrings matched
by subpatterns surrounded by parentheses.

* New function `insert-before-markers'.

This function is just like `insert' except in the handling of any
relocatable markers that are located at the point of insertion.
With `insert', such markers end up pointing before the inserted text.
With `insert-before-markers', they end up pointing after the inserted
text.

* New function `copy-alist'.

This function takes one argument, a list, and makes a disjoint copy
of the alist structure.  The list itself is copied, and each element
that is a cons cell is copied, but the cars and cdrs of elements
remain shared with the original argument.

This is what it takes to get two alists disjoint enough that changes
in one do not change the result of `assq' on the other.

* New function `copy-keymap'.

This function takes a keymap as argument and returns a new keymap
containing initially the same bindings.  Rebindings in either one of
them will not alter the bindings in the other.

* New function `copy-syntax-table'.

This function takes a syntax table as argument and returns a new
syntax table containing initially the same syntax settings.  Changes
in either one of them will not alter the other.

* Randomizing the random numbers.

`(random t)' causes the random number generator's seed to be set
based on the current time and Emacs's process id.

* Third argument to `modify-syntax-entry'.

The optional third argument to `modify-syntax-entry', if specified
should be a syntax table.  The modification is made in that syntax table
rather than in the current syntax table.

* New function `run-hooks'.

This function takes any number of symbols as arguments.
It processes the symbols in order.  For each symbol which
has a value (as a variable) that is non-nil, the value is
called as a function, with no arguments.

This is useful in major mode commands.

* Second arg to `switch-to-buffer'.

If this function is given a non-`nil' second argument, then the
selection being done is not recorded on the selection history.
The buffer's position in the history remains unchanged.  This
feature is used by the view commands, so that the selection history
after exiting from viewing is the same as it was before.

* Second arg to `display-buffer' and `pop-to-buffer'.

These two functions both accept an optional second argument which
defaults to `nil'.  If the argument is not `nil', it means that
another window (not the selected one) must be found or created to
display the specified buffer in, even if it is already shown in
the selected window.

This feature is used by `switch-to-buffer-other-window'.

* New variable `completion-ignore-case'.

If this variable is non-`nil', completion allows strings
in different cases to be considered matching.  The global value
is `nil'

This variable exists for the sake of commands that are completing
an argument in which case is not significant.  It is possible
to change the value globally, but you might not like the consequences
in the many situations (buffer names, command names, file names)
where case makes a difference.

* Major modes related to Text mode call text-mode-hook, then their own hooks.

For example, turning on Outline mode first calls the value of
`text-mode-hook' as a function, if it exists and is non-`nil',
and then does likewise for the variable `outline-mode-hook'.

* Defining new command line switches.

You can define a new command line switch in your .emacs file
by putting elements on the value of `command-switch-alist'.
Each element of this list should look like
      (SWITCHSTRING . FUNCTION)
where SWITCHSTRING is a string containing the switch to be
defined, such as "-foo", and FUNCTION is a function to be called
if such an argument is found in the command line.  FUNCTION
receives the command line argument, a string, as its argument.

To implement a switch that uses up one or more following arguments,
use the fact that the remaining command line arguments are kept
as a list in the variable `command-line-args'.  FUNCTION can
examine this variable, and do
    (setq command-line-args (cdr command-line-args)
to "use up" an argument.

* New variable `load-in-progress'.

This variable is non-`nil' when a file of Lisp code is being read
and executed by `load'.

* New variable `print-length'.

The value of this variable is normally `nil'.  It may instead be
a number; in that case, when a list is printed by `prin1' or
`princ' only that many initial elements are printed; the rest are
replaced by `...'.

* New variable `find-file-not-found-hook'.

If `find-file' or any of its variants is used on a nonexistent file,
the value of `find-file-not-found-hook' is called (if it is not `nil')
with no arguments, after creating an empty buffer.  The file's name
can be found as the value of `buffer-file-name'.

* Processes without buffers.

In the function `start-process', you can now specify `nil' as
the process's buffer.  You can also set a process's buffer to `nil'
using `set-process-buffer'.

The reason you might want to do this is to prevent the process
from being killed because any particular buffer is killed.
When a process has a buffer, killing that buffer kills the
process too.

When a process has no buffer, its output is lost unless it has a
filter, and no indication of its being stopped or killed is given
unless it has a sentinel.

* New function `user-variable-p'.  `v' arg prompting changed.

This function takes a symbol as argument and returns `t' if
the symbol is defined as a user option variable.  This means
that it has a `variable-documentation' property whose value is
a string starting with `*'.

Code `v' in an interactive arg reading string now accepts
user variables only, and completion is limited to the space of
user variables.

The function `read-variable' also now accepts and completes
over user variables only.

* CBREAK mode input is the default in Unix 4.3 bsd.

In Berkeley 4.3 Unix, there are sufficient features for Emacs to
work fully correctly using CBREAK mode and not using SIGIO.
Therefore, this mode is the default when running under 4.3.
This mode corresponds to `nil' as the first argument to
`set-input-mode'.  You can still select either mode by calling
that function.

* Information on memory usage.

The new variable `data-bytes-used' contains the number
of bytes of impure space allocated in Emacs.
`data-bytes-free' contains the number of additional bytes
Emacs could allocate.  Note that space formerly allocated
and freed again still counts as `used', since it is still
in Emacs's address space.

* No limit on size of output from `format'.

The string output from `format' used to be truncated to
100 characters in length.  Now it can have any length.

* New errors `void-variable' and `void-function' replace `void-symbol'.

This change makes it possible to have error messages that
clearly distinguish undefined variables from undefined functions.
It also allows `condition-case' to handle one case without the other.

* `replace-match' handling of `\'.

In `replace-match', when the replacement is not literal,
`\' in the replacement string is always treated as an
escape marker.  The only two special `\' constructs
are `\&' and `\DIGIT', so `\' followed by anything other than
`&' or a digit has no effect.  `\\' is necessary to include
a `\' in the replacement text.

This level of escaping is comparable with what goes on in
a regular expression.  It is over and above the level of `\'
escaping that goes on when strings are read in Lisp syntax.

* New error `invalid-regexp'.

A regexp search signals this type of error if the argument does
not meet the rules for regexp syntax.

* `kill-emacs' with argument.

If the argument is a number, it is returned as the exit status code
of the Emacs process.  If the argument is a string, its contents
are stuffed as pending terminal input, to be read by another program
after Emacs is dead.

* New fifth argument to `subst-char-in-region'.

This argument is optional and defaults to `nil'.  If it is not `nil',
then the substitutions made by this function are not recorded
in the Undo mechanism.

This feature should be used with great care.  It is now used
by Outline mode to make lines visible or invisible.

* ` *Backtrace*' buffer renamed to `*Backtrace*'.

As a result, you can now reselect this buffer easily if you switch to
another while in the debugger.

Exiting from the debugger kills the `*Backtrace*' buffer, so you will
not try to give commands in it when no longer really in the debugger.

* New function `switch-to-buffer-other-window'.

This is the new primitive to select a specified buffer (the
argument)  in another window.  It is not quite the same as
`pop-to-buffer', because it is guaranteed to create another
window (assuming there is room on the screen) so that it can
leave the current window's old buffer displayed as well.

All functions to select a buffer in another window should
do so by calling this new function.

* New variable `minibuffer-help-form'.

At entry to the minibuffer, the variable `help-form' is bound
to the value of `minibuffer-help-form'.

`help-form' is expected at all times to contain either `nil'
or an expression to be executed when C-h is typed (overriding
teh definition of C-h as a command).  `minibuffer-help-form'
can be used to provide a different default way of handling
C-h while in the minibuffer.

* New \{...} documentation construct.

It is now possible to set up the documentation string for
a major mode in such a way that it always describes the contents
of the major mode's keymap, as it has been customized.
To do this, include in the documentation string the characters `\{'
followed by the name of the variable containing the keymap,
terminated with `}'.  (The `\' at the beginning probably needs to
be quoted with a second `\', to include it in the doc string.)
This construct is normally used on a line by itself, with no blank
lines before or after.

For example, the documentation string for the function `c-mode' contains
    ...
    Paragraphs are separated by blank lines only.
    Delete converts tabs to spaces as it moves back.
    \\{c-mode-map}
    Variables controlling indentation style:
    ...

* New character syntax class "punctuation".

Punctuation characters behave like whitespace in word and
list parsing, but can be distinguished in regexps and in the
function `char-syntax'.  Punctuation syntax is represented by
a period in `modify-syntax-entry'.

* `auto-mode-alist' no longer needs entries for backup-file names,

Backup suffixes of all kinds are now stripped from a file's name
before searching `auto-mode-alist'.
\f
Changes in Emacs 16

* No special code for Ambassadors, VT-100's and Concept-100's.

Emacs now controls these terminals based on the termcap entry, like
all other terminals.  Formerly it did not refer to the termcap entries
for those terminal types, and often the termcap entries for those
terminals are wrong or inadequate.  If you experience worse behavior
on these terminals than in version 15, you can probably correct it by
fixing up the termcap entry.  See ./TERMS for more info.

See ./TERMS in any case if you find that some terminal does not work
right with Emacs now.

* Minibuffer default completion character is TAB (and not ESC).

So that ESC can be used in minibuffer for more useful prefix commands.

* C-z suspends Emacs in all modes.

Formerly, C-z was redefined for other purposes by certain modes,
such as Buffer Menu mode.  Now other keys are used for those purposes,
to keep the meaning of C-z uniform.

* C-x ESC (repeat-complex-command) allows editing the command it repeats.

Instead of asking for confirmation to re-execute a command from the
command history, the command is placed, in its Lisp form, into the
minibuffer for editing.  You can confirm by typing RETURN, change some
arguments and then confirm, or abort with C-g.

* Incremental search does less redisplay on slow terminals.

If the terminal baud rate is <= the value of `isearch-slow-speed',
incremental searching outside the text on the screen creates
a single-line window and uses that to display the line on which
a match has been found.  Exiting or quitting the search restores
the previous window configuration and redisplays the window you
were searching in.

The initial value of `isearch-slow-speed' is 1200.

This feature is courtesy of crl@purdue.

* Recursive minibuffers not allowed.

If the minibuffer window is selected, most commands that would
use the minibuffer gets an error instead.  (Specific commands
may override this feature and therefore still be allowed.)

Strictly speaking, recursive entry to the minibuffer is still
possible, because you can switch to another window after
entering the minibuffer, and then minibuffer-using commands
are allowed.  This is still allowed by a deliberate decision:
if you know enough to switch windows while in the minibuffer,
you can probably understand recursive minibuffers.

This may be overridden by binding the variable
`enable-recursive-minibuffers' to t.

* New major mode Emacs-Lisp mode, for editing Lisp code to run in Emacs.

The mode in which emacs lisp files is edited is now called emacs-lisp-mode
and is distinct from lisp-mode.  The latter is intended for use with
lisps external to emacs.

The hook which is funcalled (if non-nil) on entry to elisp-mode is now
called emacs-lisp-mode-hook.  A consequence of this changes is that
.emacs init files which set the value of lisp-mode-hook may need to be
changed to use the new names.

* Correct matching of parentheses is checked on insertion.

When you insert a close-paren, the matching open-paren
is checked for validity.  The close paren must be the kind
of close-paren that the open-paren says it should match.
Otherwise, a warning message is printed.  close-paren immediately
preceded by quoting backslash syntax character is not matched.

This feature was originally written by shane@mit-ajax.

* M-x list-command-history
* M-x command-history-mode
* M-x electric-command-history

`list-command-history' displays forms from the command history subject
to user controlled filtering and limit on number of forms.  It leaves
the buffer in `command-history-mode'.  M-x command-history-mode
recomputes the command history each time it is invoked via
`list-command-history'.  It is like Emacs-Lisp mode except that characters
don't insert themselves and provision is made for re-evaluating an
expression from the list.  `electric-command-history' pops up a type
out window with the command history displayed.  If the very next
character is Space, the window goes away and the previous window
configuration is restored.  Otherwise you can move around in the
history and select an expression for evaluation *inside* the buffer
which invoked `electric-command-history'.  The original window
configuration is restored on exit unless the command selected changes
it.

* M-x edit-picture

Enters a temporary major mode (the previous major mode is remembered
and can is restored on exit) designed for editing pictures and tables.
Printing characters replace rather than insert themselves with motion
afterwards that is user controlled (you can specify any of the 8
compass directions).  Special commands for movement are provided.
Special commands for hacking tabs and tab stops are provided.  Special
commands for killing rectangles and overlaying them are provided.  See
the documentation of function  edit-picture  for more details.

Calls value of `edit-picture-hook' on entry if non-nil.

* Stupid C-s/C-q `flow control' supported.

Do (set-input-mode nil t) to tell Emacs to use CBREAK mode and interpret
C-s and C-q as flow control commands.  (set-input-mode t nil) switches
back to interrupt-driven input.  (set-input-mode nil nil) uses CBREAK
mode but no `flow control'; this may make it easier to run Emacs under
certain debuggers that have trouble dealing with inferiors that use SIGIO.

CBREAK mode has certain inherent disadvantages, which are why it is
not the default:

     Meta-keys are ignored; CBREAK mode discards the 8th bit of
     input characters.

     Control-G as keyboard input discards buffered output,
     and therefore can cause incorrect screen updating.

The use of `flow control' has its own additional disadvantage: the
characters C-s and C-q are not available as editing commands.  You can
partially compensate for this by setting up a keyboard-translate-table
(see file ONEWS) that maps two other characters (such as C-^ and C-\) into
C-s and C-q.  Of course, C-^ and C-\ are commonly used as escape
characters in remote-terminal programs.  You really can't win except
by getting rid of this sort of `flow control.'

The configuration switch CBREAK_INPUT is now eliminated.
INTERRUPT_INPUT exists only to specify the default mode of operation;
#define it to make interrupt-driven input the default.

* Completion of directory names provides a slash.

If file name completion yields the name of a directory,
a slash is appended to it.

* Undo can clear modified-flag.

If you undo changes in a buffer back to a state in which the
buffer was not considered "modified", then it is labelled as
once again "unmodified".

* M-x run-lisp.

This command creates an inferior Lisp process whose input and output
appear in the Emacs buffer named `*lisp*'.  That buffer uses a major mode
called inferior-lisp-mode, which has many of the commands of lisp-mode
and those of shell-mode.   Calls the value of shell-mode-hook and
lisp-mode-hook, in that order, if non-nil.

Meanwhile, in lisp-mode, the command C-M-x is defined to
send the current defun as input to the `*lisp*' subprocess.

* Mode line says `Narrow' when buffer is clipped.

If a buffer has a clipping restriction (made by `narrow-to-region')
then its mode line contains the word `Narrow' after the major and
minor modes.

* Mode line says `Abbrev' when abbrev mode is on.

* add-change-log-entry takes prefix argument

Giving a prefix argument makes it prompt for login name, full name,
and site name, with defaults.  Otherwise the defaults are used
with no confirmation.

* M-x view-buffer and M-x view-file

view-buffer selects the named buffer, view-file finds the named file; the
resulting buffer is placed into view-mode (a recursive edit).  The normal
emacs commands are not available.  Instead a set of special commands is
provided which faclitate moving around in the buffer, searching and
scrolling by screenfuls.  Exiting view-mode returns to the buffer in which
the view-file or view-buffer command was given.
Type ? or h when viewing for a complete list of view commands.
Each calls value of `view-hook' if non-nil on entry.

written by shane@mit-ajax.

* New key commands in dired.

`v' views (like more) the file on the current line.
`#' marks auto-save files for deletion.
`~' marks backup files for deletion.
`r' renames a file and updates the directory listing if the
file is renamed to same directory.
`c' copies a file and updates the directory listing if the file is
copied to the same directory.

* New function `electric-buffer-list'.

This pops up a buffer describing the set of emacs buffers.
Immediately typing space makes the buffer list go away and returns
to the buffer and window which were previously selected.

Otherwise one may use the c-p and c-n commands to move around in the
buffer-list buffer and type Space or C-z to select the buffer on the
cursor's line.  There are a number of other commands which are the same
as those of buffer-menu-mode.

This is a useful thing to bind to c-x c-b in your `.emacs' file if the
rather non-standard `electric' behaviour of the buffer list suits your taste.
Type C-h after invoking electric-buffer-list for more information.

Calls value of `electric-buffer-menu-mode-hook' if non-nil on entry.
Calls value of `after-electric-buffer-menu' on exit (select) if non-nil.
\f
Changes in version 16 for mail reading and sending

* sendmail prefix character is C-c (and not C-z).  New command C-c w.

For instance C-c C-c (or C-c C-s) sends mail now rather than C-z C-z.
C-c w inserts your `signature' (contents of ~/.signature) at the end
of mail.

* New feature in C-c y command in sending mail.

C-c y is the command to insert the message being replied to.
Normally it deletes most header fields and indents everything
by three spaces.

Now, C-c y does not delete header fields or indent.
C-c y with any other numeric argument does delete most header
fields, but indents by the amount specified in the argument.

* C-r command in Rmail edits current message.

It does this by switching to a different major mode
which is nearly the same as Text mode.  The only difference
between it and text mode are the two command C-c and C-].
C-c is defined to switch back to Rmail mode, and C-]
is defined to restore the original contents of the message
and then switch back to Rmail mode.

C-c and C-] are the only ways "back into Rmail", but you
can switch to other buffers and edit them as usual.
C-r in Rmail changes only the handling of the Rmail buffer.

* Rmail command `t' toggles header display.

Normally Rmail reformats messages to hide most header fields.
`t' switches to display of all the header fields of the
current message, as long as it remains current.
Another `t' switches back to the usual display.

* Rmail command '>' goes to the last message.

* Rmail commands `a' and `k' set message attributes.
`a' adds an attribute and `k' removes one.  You specify
the attrbute by name.  You can specify either a built-in
flag such as "deleted" or "filed", or a user-defined keyword
(anything not recognized as built-in).

* Rmail commands `l' and `L' summarize by attributes.

These commands create a summary with one line per message,
like `h', but they list only some of the messages.  You
specify which attribute (for `l') or attributes (for `L')
the messages should have.

* Rmail can parse mmdf mail files.

* Interface to MH mail system.

mh-e is a front end for GNU emacs and the MH mail system.  It
provides a friendly and convient interface to the MH commands.

To read mail, invoke mh-rmail.  This will inc new mail and display the
scan listing on the screen.  To see a summary of the mh-e commands,
type ?.  Help is available through the usual facilities.

To send mail, invoke mh-smail.

mh-e requires a copy of MH.5 that has been compiled with the MHE
compiler switch.

From larus@berkeley.
\f
New hooks and parameters in version 16

* New variable `blink-matching-paren-distance'.

This is the maximum number of characters to search for
an open-paren to match an inserted close-paren.
The matching open-paren is shown and checked if it is found
within this distance.

`nil' means search all the way to the beginning of the buffer.
In this case, a warning message is printed if no matching
open-paren is found.

This feature was originally written by shane@mit-ajax.

* New variable `find-file-run-dired'

If nil, find-file will report an error if an attempt to visit a
directory is detected; otherwise, it runs dired on that directory.
The default is t.

* Variable `dired-listing-switches' holds switches given to `ls' by dired.

The value should be a string containing `-' followed by letters.
The letter `l' had better be included and letter 'F' had better be excluded!
The default is "-al".

This feature was originally written by shane@mit-ajax.

* New variable `display-time-day-and-date'.

If this variable is set non-`nil', the function M-x display-time
displays the day and date, as well as the time.

* New parameter `c-continued-statement-indent'.

This controls the extra indentation given to a line
that continues a C statement started on the previous line.
By default it is 2, which is why you would see

        if (foo)
          bar ();


* Changed meaning of `c-indent-level'.

The value of `c-brace-offset' used to be
subtracted from the value of `c-indent-level' whenever
that value was used.  Now it is not.

As a result, `c-indent-level' is now the offset of
statements within a block, relative to the line containing
the open-brace that starts the block.

* turn-on-auto-fill is useful value for text-mode-hook.

(setq text-mode-hook 'turn-on-auto-fill)
is all you have to do to make sure Auto Fill mode is turned
on whenever you enter Text mode.

* Parameter explicit-shell-file-name for M-x shell.

This variable, if non-nil, specifies the file name to use
for the shell to run if you do M-x shell.
\f
Changes in version 16 affecting Lisp programming:

* Documentation strings adapt to customization.

Often the documentation string for a command wants to mention
another command.  Simply stating the other command as a
character sequence has a disadvantage: if the user customizes
Emacs by moving that function to a different command, the
cross reference in the documentation becomes wrong.

A new feature allows you to write the documentation string
using a function name, and the command to run that function
is looked up when the documentation is printed.

If a documentation string contains `\[' (two characters) then
the following text, up to the next `]', is taken as a function name.
Instead of printing that function name, the command that runs it is printed.
(M-x is used to construct a command if no shorter one exists.)

For example, instead of putting `C-n' in a documentation string
to refer to the C-n command, put in `\[next-line]'.  (In practice
you will need to quote the backslash with another backslash,
due to the syntax for strings in Lisp and C.)

To include the literal characters `\[' in a documentation string,
precede them with `\='.  To include the characters `\=', precede
them with `\='.  For example, "\\=\\= is the way to quote \\=\\["
will come out as `\= is the way to quote \['.

The new function `substitute-command-keys' takes a string possibly
contaning \[...] constructs and replaces those constructs with
the key sequences they currently stand for.

* Primitives `find-line-comment' and `find-line-comment-body' flushed.

Search for the value of `comment-start-skip' if you want to find
whether and where a line has a comment.

* New function `auto-save-file-name-p'

Should return non-`nil' iff given a string which is the name of an
auto-save file (sans directory name).  If you redefine
`make-auto-save-file-name', you should redefine this accordingly.  By
default, this function returns `t' for filenames beginning with
character `#'.

* The value of `exec-directory' now ends in a slash.

This is to be compatible with most directory names in GNU Emacs.

* Dribble files and termscript files.

(open-dribble-file FILE) opens a dribble file named FILE.  When a
dribble file is open, every character Emacs reads from the terminal is
written to the dribble file.

(open-termscript FILE) opens a termscript file named FILE.  When a
termscript file is open, all characters sent to the terminal by Emacs
are also written in the termscript file.

The two of these together are very useful for debugging Emacs problems
in redisplay.

* Upper case command characters by default are same as lower case.

If a character in a command is an upper case letter, and is not defined,
Emacs uses the definition of the corresponding lower case letter.
For example, if C-x U is not directly undefined, it is treated as
a synonym for C-x u (undo).

* Undefined function errors versus undefined variable errors.

Void-symbol errors now say "boundp" if the symbol's value was void
or "fboundp" if the function definition was void.

* New function `bury-buffer'.

The new function `bury-buffer' takes one argument, a buffer object,
and puts that buffer at the end of the internal list of buffers.
So it is the least preferred candidate for use as the default value
of C-x b, or for other-buffer to return.

* Already-displayed buffers have low priority for display.

When a buffer is chosen automatically for display, or to be the
default in C-x b, buffers already displayed in windows have lower
priority than buffers not currently visible.

* `set-window-start' accepts a third argument NOFORCE.

This argument, if non-nil, prevents the window's force_start flag
from being set.  Setting the force_start flag causes the next
redisplay to insist on starting display at the specified starting
point, even if dot must be moved to get it onto the screen.

* New function `send-string-to-terminal'.

This function takes one argument, a string, and outputs its contents
to the terminal exactly as specified: control characters, escape
sequences, and all.

* Keypad put in command mode.

The terminal's keypad is now put into command mode, as opposed to
numeric mode, while Emacs is running.  This is done by means of the
termcap `ks' and `ke' strings.

* New function `generate-new-buffer'

This function takes a string as an argument NAME and looks for a
creates and returns a buffer called NAME if one did not already exist.
Otherwise, it successively tries appending suffixes of the form "<1>",
"<2>" etc to NAME until it creates a string which does not name an
existing buffer.  A new buffer with that name is the created and returned.

* New function `prin1-to-string'
This function takes one argument, a lisp object, and returns a string
containing that object's printed representation, such as `prin1'
would output.

* New function `read-from-minibuffer'
Lets you supply a prompt, initial-contents, a keymap, and specify
whether the result should be interpreted as a string or a lisp object.

Old functions `read-minibuffer', `eval-minibuffer', `read-string' all
take second optional string argument which is initial contents of
minibuffer.

* minibuffer variable names changed (names of keymaps)

minibuf-local-map -> minibuffer-local-map
minibuf-local-ns-map -> minibuffer-local-ns-map
minibuf-local-completion-map -> minibuffer-local-completion-map
minibuf-local-must-match-map -> minibuffer-local-must-match-map
\f
Changes in version 16 affecting configuring and building Emacs

* Configuration switch VT100_INVERSE eliminated.

You can control the use of inverse video on any terminal by setting
the variable `inverse-video', or by changing the termcap entry.  If
you like, set `inverse-video' in your `.emacs' file based on
examination of (getenv "TERM").

* New switch `-batch' makes Emacs run noninteractively.

If the switch `-batch' is used, Emacs treats its standard output
and input like ordinary files (even if they are a terminal).
It does not display buffers or windows; the only output to standard output
is what would appear as messages in the echo area, and each
message is followed by a newline.

The terminal modes are not changed, so that C-z and C-c retain
their normal Unix meanings.  Emacs does still read commands from
the terminal, but the idea of `-batch' is that you use it with
other command line arguments that tell Emacs a complete task to perform,
including killing itself.  `-kill' used as the last argument is a good
way to accomplish this.

The Lisp variable `noninteractive' is now defined, to be `nil'
except when `-batch' has been specified.

* Emacs can be built with output redirected to a file.

This is because -batch (see above) is now used in building Emacs.
\f
For older news, see the file ONEWS.1.

----------------------------------------------------------------------
Copyright information:

Copyright (C) 1985 Richard M. Stallman

   Permission is granted to anyone to make or distribute verbatim copies
   of this document as received, in any medium, provided that the
   copyright notice and this permission notice are preserved,
   thus giving the recipient permission to redistribute in turn.

   Permission is granted to distribute modified versions
   of this document, or of portions of it,
   under the above conditions, provided also that they
   carry prominent notices stating who last changed them.
\f
Local variables:
mode: text
end:

arch-tag: 33dc900d-9c58-473b-87c9-b6d7222323ea