man/man1/acmeevent.1

.TH ACMEEVENT 1
.SH NAME
acmeevent, acme.rc \- shell script support for acme clients
.SH SYNOPSIS
.B 9p
.B read
.B acme/acme/$winid/event | acmeevent
.PP
.B
\&. \*9/lib/acme.rc
.PP
.B newwindow
.PP
.B winread
.I file
.PP
.B winwrite
.I file
.PP
.B winctl
.I cmd
.PP
.B windump
[
.I dumpdir
|
.B -
]
[
.I dumpcmd
|
.B -
]
.PP
.B winname
.I name
.PP
.B windel
[
.B sure
]
.PP
.B winwriteevent
.I c1
.I c2
.I q0
.I q1
[
.I eq0
.I eq1
.I flag
.I textlen
.I text
.I chordarg
.I chordaddr
]
.PP
.B wineventloop
.SH DESCRIPTION
.I Acmeevent
and
.I acme.rc
make it easy to write simple
.IR acme (1)
client programs as shell scripts.
.PP
.I Acme
clients read the
.B event
files 
(see
.IR acme (4))
for the windows they control, reacting to the events.
The events are presented in a format that is easy to read with C programs
but hard to read with shell scripts.
.PP
.I Acmeevent
reads an
.IR acme (4)
event stream from standard input, printing a shell-friendly
version of the events, one per line, on standard output.
Each output line from
.I acmeevent
has the form:
.IP
.B event
.I c1
.I c2
.I q0
.I q1
.I eq0
.I eq1
.I flag
.I textlen
.I text
.I chordarg
.I chordaddr
.PP
The fields are:
.TP
.I c1
A character indicating the origin or cause of the action.
The possible causes are:
a write to the body or tag file
.RB ( E ),
a write to the window's other files
.RB ( F ),
input via the keyboard
.RB ( K ),
and
input via the mouse
.RB ( M ).
.TP
.I c2
A character indicating the type of action.
The possible types are:
text deleted from the body
.RB ( D ),
text deleted from the tag
.RB ( d ),
text inserted in the body
.RB ( I ),
text inserted in the tag
.RB ( i ),
a button 3 action in the body
.RB ( L ),
a button 3 action in the tag
.RB ( l ),
a button 2 action in the body
.RB ( X ),
and 
a button 2 action in the tag
.RB ( x ).
.TP
.I q0\fR, \fPq1
The character addresses of the action.
.TP
.I eq0\fR, \fPq1
The expanded character addresses of the action.
If the text indicated by
.IR q0 ,
.I q1
is a null string that has a non-null expansion,
.IR eq0 ,
.I eq1
are the addresses of the expansion.
Otherwise they are the same as
.IR q0 ,
.IR q1 .
.TP
.I flag
.I Flag
is a bitwise OR (reported decimally) of the following:
1 if the text indicated is recognized as an
.I acme
built-in command;
2 if the text indicated is a null string that has a non-null expansion
(see
.IR eq0 ,
.I eq1
above);
8 if the command has an extra (chorded) argument
(see
.I chordarg
below).
.I Flag
remains from the
.IR acme (4)
event format.
Because
.IR eq0 ,
.IR eq1 ,
and
.I chordarg
are explicit in each event
(unlike in
.IR acme (4)
events),
.I flag
can usually be ignored.
.TP
.I textlen
The length of the action text (or its expansion) for button 2 and button 3 events in characters.
.TP
.I text
If
.I textlen
is less than 256 chracters,
.I text
is the action text itself.
Otherwise it is an empty string and must be read from the
.B data
file.
.TP
.I chordarg
The chorded argument for an action.
.TP
.I chordorigin
If the chord argument is in the body of a named window,
.I chordorigin
specifies the full address of the argument,
as in
.BR /etc/group:#123,#234 .
.PD
.PP
To experiment with
.IR acmeevent ,
create an empty window in
.I acme
(using
.IR New ), type
.IP
.EX
9p read acme/$winid/event | acmeevent
.EE
.LP
inside it, and execute it.
Actions performed on the window will be printed as events in the
.B +Errors
window.
.PP
.I Acme.rc
is a library of
.IR rc (1)
shell functions useful for writing acme clients.
.PP
.I Newwindow
creates a new acme window and sets
.B $winid
to the new window's id.
The other commands all use
.B $winid
to determine which window to operate on.
.PP
.I Winread
prints the current window's
.I file
to standard output.
It is equivalent to
.B cat
.BI /mnt/acme/acme/$winid/ file
on Plan 9.
Similarly,
.I winwrite
writes standard input to the current window's
.IR file .
.I Winread
and
.I winwrite
are useful mainly in building more complex functions.
.PP
.I Winctl
writes 
.I cmd
to the window's
.B ctl
file.
The most commonly-used command is
.BR clean ,
which marks the window as clean.
See
.IR acme (4)
for a full list of commands.
.PP
.I Windump
sets the window's dump directory
and dump command
(see
.IR acme (4)).
If either argument is omitted or is
.BR - ,
that argument is not set.
.PP
.I Winname
sets the name displayed in the window's tag.
.PP
.I Windel
simulates the
.B Del
command.  If the argument
.B sure
is given, it simulates the
.B Delete
command.
.PP
.I Winwriteevent
writes an event to the window's event file.
The event is in the format produced by
.IR acmeevent .
Only the first four arguments are necessary:
the rest are ignored.
Event handlers should call
.I winwriteevent
to pass unhandled button 2 or button 3 events
back to
.I acme
for processing.
.PP
.I Wineventloop
executes the current window's event file, as output by
.IR acmeevent .
It returns when the window has been deleted.
Before running
.I wineventloop ,
clients must define a shell function named
.BR event ,
which will be run for each incoming event,
as
.I rc
executes the output of
.IR acmeevent .
A typical event function need only worry about button 2 and button 3 events.
Those events not handled should be sent back to 
.I acme
with
.IR winwriteevent .
.SH EXAMPLE
.IR Adict ,
a dictionary browser,
is implemented using 
.I acmeevent
and
.IR acme.rc .
The
.I event
handler is:
.IP
.EX
.ta +4n +4n +4n +4n +4n +4n
fn event {
	switch($1$2){
	case Mx MX    # button 2 - pass back to acme
		winwriteevent $*
	case Ml ML    # button 3 - open new window on dictionary or entry
		{
			if(~ $dict NONE)
				dictwin /adict/$7/ $7
			if not
				dictwin /adict/$dict/$7 $dict $7
		} &
	}
}
.EE
.LP
Note that the button 3 handler starts a subshell in which to run
.IR dictwin .
That subshell will create a new window, set its name,
possibly fill the window with a dictionary list or dictionary entry,
mark the window as clean, and run the event loop:
.IP
.EX
fn dictwin {
	newwindow
	winname $1
	dict=$2
	if(~ $dict NONE)
		dict -d '?' >[2=1] | sed 1d | winwrite body
	if(~ $#* 3)
		dict -d $dict $3 >[2=1] | winwrite body
	winctl clean
	wineventloop
}
.EE
.LP
The script starts with an initial window:
.IP
.EX
dictwin /adict/ NONE
.EE
.LP
Button 3 clicking on a dictionary name in the initial window
will create a new empty window for that dictionary.
Typing and button 3 clicking on a word in that window
will create a new window with the dictionary's entry for that word.
.PP
See
.B \*9/bin/adict
for the full implementation.
.SH SOURCE
.B \*9/src/cmd/acmeevent.c
.br
.B \*9/lib/acme.rc
.SH SEE ALSO
.IR acme (1),
.IR acme (4),
.IR rc (1)
.SH BUGS
There is more that could be done to ease the writing
of complicated clients.