* Refresh Screen:: Clearing the screen and redrawing everything on it.
* Forcing Redisplay:: Forcing redisplay.
* Truncation:: Folding or wrapping long text lines.
-* The Echo Area:: Where messages are displayed.
+* The Echo Area:: Displaying messages at the bottom of the screen.
* Warnings:: Displaying warning messages for the user.
-* Progress:: Informing user about progress of a long operation.
* Invisible Text:: Hiding part of the buffer text.
* Selective Display:: Hiding part of the buffer text (the old way).
* Temporary Displays:: Displays that go away automatically.
@cindex error display
@cindex echo area
-The @dfn{echo area} is used for displaying error messages
+ The @dfn{echo area} is used for displaying error messages
(@pxref{Errors}), for messages made with the @code{message} primitive,
and for echoing keystrokes. It is not the same as the minibuffer,
despite the fact that the minibuffer appears (when active) in the same
the minibuffer for use of that screen space (@pxref{Minibuffer,, The
Minibuffer, emacs, The GNU Emacs Manual}).
-You can write output in the echo area by using the Lisp printing
-functions with @code{t} as the stream (@pxref{Output Functions}), or as
-follows:
+ You can write output in the echo area by using the Lisp printing
+functions with @code{t} as the stream (@pxref{Output Functions}), or
+explicitly.
+
+@menu
+* Displaying Messages:: Explicitly displaying text in the echo area.
+* Progress Reports:: Informing user about progress of a long operation.
+* Logging Messages:: Echo area messages are logged for the user.
+* Echo Area Customization:: Controlling the echo area.
+@end menu
+
+@node Displaying Messages
+@subsection Displaying Messages in the Echo Area
+
+ This section describes the functions for explicitly producing echo
+area messages. Many other Emacs features display messages there, too.
@defun message string &rest arguments
This function displays a message in the echo area. The
its normal size. If the minibuffer is active, this brings the
minibuffer contents back onto the screen immediately.
-@vindex message-truncate-lines
-Normally, displaying a long message resizes the echo area to display
-the entire message. But if the variable @code{message-truncate-lines}
-is non-@code{nil}, the echo area does not resize, and the message is
-truncated to fit it, as in Emacs 20 and before.
-
@example
@group
(message "Minibuffer depth is %d."
depending on its size, use @code{display-message-or-buffer} (see below).
@end defun
-@defopt max-mini-window-height
-This variable specifies the maximum height for resizing minibuffer
-windows. If a float, it specifies a fraction of the height of the
-frame. If an integer, it specifies a number of lines.
-@end defopt
-
@tindex with-temp-message
@defmac with-temp-message message &rest body
This construct displays a message in the echo area temporarily, during
echo area, or @code{nil} if there is none.
@end defun
-@defvar cursor-in-echo-area
-This variable controls where the cursor appears when a message is
-displayed in the echo area. If it is non-@code{nil}, then the cursor
-appears at the end of the message. Otherwise, the cursor appears at
-point---not in the echo area at all.
+@node Progress
+@subsection Reporting Operation Progress
+@cindex progress reporting
-The value is normally @code{nil}; Lisp programs bind it to @code{t}
-for brief periods of time.
-@end defvar
+ When an operation can take a while to finish, you should inform the
+user about the progress it makes. This way the user can estimate
+remaining time and clearly see that Emacs is busy working, not hung.
-@defvar echo-area-clear-hook
-This normal hook is run whenever the echo area is cleared---either by
-@code{(message nil)} or for any other reason.
-@end defvar
+ Functions listed in this section provide simple and efficient way of
+reporting operation progress. Here is a working example that does
+nothing useful:
-Almost all the messages displayed in the echo area are also recorded
-in the @samp{*Messages*} buffer.
+@smallexample
+(let ((progress-reporter
+ (make-progress-reporter "Collecting mana for Emacs..."
+ 0 500)))
+ (dotimes (k 500)
+ (sit-for 0.01)
+ (progress-reporter-update progress-reporter k))
+ (progress-reporter-done progress-reporter))
+@end smallexample
+
+@defun make-progress-reporter message min-value max-value &optional current-value min-change min-time
+This function creates and returns a @dfn{progress reporter}---an
+object you will use as an argument for all other functions listed
+here. The idea is to precompute as much data as possible to make
+progress reporting very fast.
+
+When this progress reporter is subsequently used, it will display
+@var{message} in the echo area, followed by progress percentage.
+@var{message} is treated as a simple string. If you need it to depend
+on a filename, for instance, use @code{format} before calling this
+function.
+
+@var{min-value} and @var{max-value} arguments stand for starting and
+final states of your operation. For instance, if you scan a buffer,
+they should be the results of @code{point-min} and @code{point-max}
+correspondingly. It is required that @var{max-value} is greater than
+@var{min-value}. If you create progress reporter when some part of
+the operation has already been completed, then specify
+@var{current-value} argument. But normally you should omit it or set
+it to @code{nil}---it will default to @var{min-value} then.
+
+Remaining arguments control the rate of echo area updates. Progress
+reporter will wait for at least @var{min-change} more percents of the
+operation to be completed before printing next message.
+@var{min-time} specifies the minimum time in seconds to pass between
+successive prints. It can be fractional. Depending on Emacs and
+system capabilities, progress reporter may or may not respect this
+last argument or do it with varying precision. Default value for
+@var{min-change} is 1 (one percent), for @var{min-time}---0.2
+(seconds.)
+
+This function calls @code{progress-reporter-update}, so the first
+message is printed immediately.
+@end defun
+
+@defun progress-reporter-update reporter value
+This function does the main work of reporting progress of your
+operation. It displays the message of @var{reporter}, followed by
+progress percentage determined by @var{value}. If percentage is zero,
+or close enough according to the @var{min-change} and @var{min-time}
+arguments, then it is omitted from the output.
+
+@var{reporter} must be the result of a call to
+@code{make-progress-reporter}. @var{value} specifies the current
+state of your operation and must be between @var{min-value} and
+@var{max-value} (inclusive) as passed to
+@code{make-progress-reporter}. For instance, if you scan a buffer,
+then @var{value} should be the result of a call to @code{point}.
+
+This function respects @var{min-change} and @var{min-time} as passed
+to @code{make-progress-reporter} and so does not output new messages
+on every invocation. It is thus very fast and normally you should not
+try to reduce the number of calls to it: resulting overhead will most
+likely negate your effort.
+@end defun
+
+@defun progress-reporter-force-update reporter value &optional new-message
+This function is similar to @code{progress-reporter-update} except
+that it prints a message in the echo area unconditionally.
+
+The first two arguments have the same meaning as for
+@code{progress-reporter-update}. Optional @var{new-message} allows
+you to change the message of the @var{reporter}. Since this functions
+always updates the echo area, such a change will be immediately
+presented to the user.
+@end defun
+
+@defun progress-reporter-done reporter
+This function should be called when the operation is finished. It
+prints the message of @var{reporter} followed by word ``done'' in the
+echo area.
+
+You should always call this function and not hope for
+@code{progress-reporter-update} to print ``100%.'' Firstly, it may
+never print it, there are many good reasons for this not to happen.
+Secondly, ``done'' is more explicit.
+@end defun
+
+@defmac dotimes-with-progress-reporter (var count [result]) message body...
+This is a convenience macro that works the same way as @code{dotimes}
+does, but also reports loop progress using the functions described
+above. It allows you to save some typing.
+
+You can rewrite the example in the beginning of this node using
+this macro this way:
+
+@example
+(dotimes-with-progress-reporter
+ (k 500)
+ "Collecting some mana for Emacs..."
+ (sit-for 0.01))
+@end example
+@end defmac
+
+@node Logging Messages
+@subsection Logging Messages in @samp{*Messages*}
+@cindex logging echo-area messages
+
+ Almost all the messages displayed in the echo area are also recorded
+in the @samp{*Messages*} buffer so that the user can refer back to
+them. This includes all the messages that are output with
+@code{message}.
@defopt message-log-max
This variable specifies how many lines to keep in the @samp{*Messages*}
@end example
@end defopt
+ To make @samp{*Messages*} more convenient for the user, the logging
+facility combines successive identical messages. It also combines
+successive related messages for the sake of two cases: question
+followed by answer, and a series of progress messages.
+
+ A ``question followed by an answer'' means two messages like the
+ones produced by @code{y-or-n-p}: the first is @samp{@var{question}},
+and the second is @samp{@var{question}...@var{answer}}. The first
+message conveys no additional information beyond what's in the second,
+so logging the second message discards the first from the log.
+
+ A ``series of progress messages'' means successive messages like
+those produced by @code{make-progress-reporter}. They have the form
+@samp{@var{base}...@var{how-far}}, where @var{base} is the same each
+time, while @var{how-far} varies. Logging each message in the series
+discards the previous one, provided they are consecutive.
+
+ The functions @code{make-progress-reporter} and @code{y-or-n-p}
+don't have to do anything special to activate the message log
+combination feature. It operates whenever two consecutive messages
+are logged that share a common prefix ending in @samp{...}.
+
+@node Echo Area Customization
+@subsection Echo Area Customization
+
+ These variables control details of how the echo area works.
+
+@defvar cursor-in-echo-area
+This variable controls where the cursor appears when a message is
+displayed in the echo area. If it is non-@code{nil}, then the cursor
+appears at the end of the message. Otherwise, the cursor appears at
+point---not in the echo area at all.
+
+The value is normally @code{nil}; Lisp programs bind it to @code{t}
+for brief periods of time.
+@end defvar
+
+@defvar echo-area-clear-hook
+This normal hook is run whenever the echo area is cleared---either by
+@code{(message nil)} or for any other reason.
+@end defvar
+
@defvar echo-keystrokes
This variable determines how much time should elapse before command
characters echo. Its value must be an integer or floating point number,
If the value is zero, then command input is not echoed.
@end defvar
+@defopt max-mini-window-height
+This variable specifies the maximum height for resizing minibuffer
+windows. If a float, it specifies a fraction of the height of the
+frame. If an integer, it specifies a number of lines.
+@end defopt
+
+@defvar message-truncate-lines
+Normally, displaying a long message resizes the echo area to display
+the entire message. But if the variable @code{message-truncate-lines}
+is non-@code{nil}, the echo area does not resize, and the message is
+truncated to fit it, as in Emacs 20 and before.
+@end defvar
+
@node Warnings
@section Reporting Warnings
@cindex warnings
that warning is not logged.
@end defopt
-@node Progress
-@section Reporting Operation Progress
-@cindex progress reporting
-
- When an operation can take a while to finish, you should inform the
-user about the progress it makes. This way the user can estimate
-remaining time and clearly see that Emacs is busy working, not hung.
-
- Functions listed in this section provide simple and efficient way of
-reporting operation progress. Here is a working example that does
-nothing useful:
-
-@smallexample
-(let ((progress-reporter
- (make-progress-reporter "Collecting mana for Emacs..."
- 0 500)))
- (dotimes (k 500)
- (sit-for 0.01)
- (progress-reporter-update progress-reporter k))
- (progress-reporter-done progress-reporter))
-@end smallexample
-
-@defun make-progress-reporter message min-value max-value &optional current-value min-change min-time
-This function creates and returns a @dfn{progress reporter}---an
-object you will use as an argument for all other functions listed
-here. The idea is to precompute as much data as possible to make
-progress reporting very fast.
-
-When this progress reporter is subsequently used, it will display
-@var{message} in the echo area, followed by progress percentage.
-@var{message} is treated as a simple string. If you need it to depend
-on a filename, for instance, use @code{format} before calling this
-function.
-
-@var{min-value} and @var{max-value} arguments stand for starting and
-final states of your operation. For instance, if you scan a buffer,
-they should be the results of @code{point-min} and @code{point-max}
-correspondingly. It is required that @var{max-value} is greater than
-@var{min-value}. If you create progress reporter when some part of
-the operation has already been completed, then specify
-@var{current-value} argument. But normally you should omit it or set
-it to @code{nil}---it will default to @var{min-value} then.
-
-Remaining arguments control the rate of echo area updates. Progress
-reporter will wait for at least @var{min-change} more percents of the
-operation to be completed before printing next message.
-@var{min-time} specifies the minimum time in seconds to pass between
-successive prints. It can be fractional. Depending on Emacs and
-system capabilities, progress reporter may or may not respect this
-last argument or do it with varying precision. Default value for
-@var{min-change} is 1 (one percent), for @var{min-time}---0.2
-(seconds.)
-
-This function calls @code{progress-reporter-update}, so the first
-message is printed immediately.
-@end defun
-
-@defun progress-reporter-update reporter value
-This function does the main work of reporting progress of your
-operation. It displays the message of @var{reporter}, followed by
-progress percentage determined by @var{value}. If percentage is zero,
-or close enough according to the @var{min-change} and @var{min-time}
-arguments, then it is omitted from the output.
-
-@var{reporter} must be the result of a call to
-@code{make-progress-reporter}. @var{value} specifies the current
-state of your operation and must be between @var{min-value} and
-@var{max-value} (inclusive) as passed to
-@code{make-progress-reporter}. For instance, if you scan a buffer,
-then @var{value} should be the result of a call to @code{point}.
-
-This function respects @var{min-change} and @var{min-time} as passed
-to @code{make-progress-reporter} and so does not output new messages
-on every invocation. It is thus very fast and normally you should not
-try to reduce the number of calls to it: resulting overhead will most
-likely negate your effort.
-@end defun
-
-@defun progress-reporter-force-update reporter value &optional new-message
-This function is similar to @code{progress-reporter-update} except
-that it prints a message in the echo area unconditionally.
-
-The first two arguments have the same meaning as for
-@code{progress-reporter-update}. Optional @var{new-message} allows
-you to change the message of the @var{reporter}. Since this functions
-always updates the echo area, such a change will be immediately
-presented to the user.
-@end defun
-
-@defun progress-reporter-done reporter
-This function should be called when the operation is finished. It
-prints the message of @var{reporter} followed by word ``done'' in the
-echo area.
-
-You should always call this function and not hope for
-@code{progress-reporter-update} to print ``100%.'' Firstly, it may
-never print it, there are many good reasons for this not to happen.
-Secondly, ``done'' is more explicit.
-@end defun
-
-@defmac dotimes-with-progress-reporter (var count [result]) message body...
-This is a convenience macro that works the same way as @code{dotimes}
-does, but also reports loop progress using the functions described
-above. It allows you to save some typing.
-
-You can rewrite the example in the beginning of this node using
-this macro this way:
-
-@example
-(dotimes-with-progress-reporter
- (k 500)
- "Collecting some mana for Emacs..."
- (sit-for 0.01))
-@end example
-@end defmac
-
@node Invisible Text
@section Invisible Text
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