[OpenSPARC-T2-DV] / tools / src / nas,5.n2.os.2 / lib / python / man / man3 / Tcl_DoOneEvent.3

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.TH Tcl_DoOneEvent 3 7.5 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_DoOneEvent \- wait for events and invoke event handlers
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
int
\fBTcl_DoOneEvent\fR(\fIflags\fR)
.SH ARGUMENTS
.AS int flags
.AP int flags in
This parameter is normally zero.  It may be an OR-ed combination
of any of the following flag bits:  
TCL_WINDOW_EVENTS,
TCL_FILE_EVENTS, TCL_TIMER_EVENTS, TCL_IDLE_EVENTS, TCL_ALL_EVENTS, or
TCL_DONT_WAIT.
.BE

.SH DESCRIPTION
.PP
This procedure is the entry point to Tcl's event loop; it is responsible for
waiting for events and dispatching event handlers created with
procedures such as \fBTk_CreateEventHandler\fR, \fBTcl_CreateFileHandler\fR,
\fBTcl_CreateTimerHandler\fR, and \fBTcl_DoWhenIdle\fR.
\fBTcl_DoOneEvent\fR checks to see if
events are already present on the Tcl event queue; if so,
it calls the handler(s) for the first (oldest) event, removes it from
the queue, and returns.
If there are no events ready to be handled, then \fBTcl_DoOneEvent\fR
checks for new events from all possible sources.
If any are found, it puts all of them on Tcl's event queue, calls
handlers for the first event on the queue, and returns.
If no events are found, \fBTcl_DoOneEvent\fR checks for \fBTcl_DoWhenIdle\fR
callbacks; if any are found, it invokes all of them and returns.
Finally, if no events or idle callbacks have been found, then
\fBTcl_DoOneEvent\fR sleeps until an event occurs; then it adds any 
new events to the Tcl event queue, calls handlers for the first event,
and returns.
The normal return value is 1 to signify that some event
was processed (see below for other alternatives).
.PP
If the \fIflags\fR argument to \fBTcl_DoOneEvent\fR is non-zero,
it restricts the kinds of events that will be processed by
\fBTcl_DoOneEvent\fR.
\fIFlags\fR may be an OR-ed combination of any of the following bits:
.TP 27
\fBTCL_WINDOW_EVENTS\fR \-
Process window system events.
.TP 27
\fBTCL_FILE_EVENTS\fR \-
Process file events.
.TP 27
\fBTCL_TIMER_EVENTS\fR \-
Process timer events.
.TP 27
\fBTCL_IDLE_EVENTS\fR \-
Process idle callbacks.
.TP 27
\fBTCL_ALL_EVENTS\fR \-
Process all kinds of events:  equivalent to OR-ing together all of the
above flags or specifying none of them.
.TP 27
\fBTCL_DONT_WAIT\fR \-
Don't sleep:  process only events that are ready at the time of the
call.
.LP
If any of the flags \fBTCL_WINDOW_EVENTS\fR, \fBTCL_FILE_EVENTS\fR,
\fBTCL_TIMER_EVENTS\fR, or \fBTCL_IDLE_EVENTS\fR is set, then the only
events that will be considered are those for which flags are set.
Setting none of these flags is equivalent to the value
\fBTCL_ALL_EVENTS\fR, which causes all event types to be processed.
If an application has defined additional event sources with
\fBTcl_CreateEventSource\fR, then additional \fIflag\fR values
may also be valid, depending on those event sources.
.PP
The \fBTCL_DONT_WAIT\fR flag causes \fBTcl_DoOneEvent\fR not to put
the process to sleep:  it will check for events but if none are found
then it returns immediately with a return value of 0 to indicate
that no work was done.
\fBTcl_DoOneEvent\fR will also return 0 without doing anything if
the only alternative is to block forever (this can happen, for example,
if \fIflags\fR is \fBTCL_IDLE_EVENTS\fR and there are no
\fBTcl_DoWhenIdle\fR callbacks pending, or if no event handlers or
timer handlers exist).
.PP
\fBTcl_DoOneEvent\fR may be invoked recursively.  For example,
it is possible to invoke \fBTcl_DoOneEvent\fR recursively
from a handler called by \fBTcl_DoOneEvent\fR.  This sort
of operation is useful in some modal situations, such
as when a
notification dialog has been popped up and an application wishes to
wait for the user to click a button in the dialog before
doing anything else.

.SH KEYWORDS
callback, event, handler, idle, timer
Commit	Line	Data
86530b38 AT	1	'\"
	2	'\" Copyright (c) 1990-1992 The Regents of the University of California.
	3	'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
	4	'\"
	5	'\" See the file "license.terms" for information on usage and redistribution
	6	'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
	7	'\"
	8	'\" RCS: @(#) $Id: DoOneEvent.3,v 1.2 1998/09/14 18:39:48 stanton Exp $
	9	'\"
	10	'\" The definitions below are for supplemental macros used in Tcl/Tk
	11	'\" manual entries.
	12	'\"
	13	'\" .AP type name in/out ?indent?
	14	'\" Start paragraph describing an argument to a library procedure.
	15	'\" type is type of argument (int, etc.), in/out is either "in", "out",
	16	'\" or "in/out" to describe whether procedure reads or modifies arg,
	17	'\" and indent is equivalent to second arg of .IP (shouldn't ever be
	18	'\" needed; use .AS below instead)
	19	'\"
	20	'\" .AS ?type? ?name?
	21	'\" Give maximum sizes of arguments for setting tab stops. Type and
	22	'\" name are examples of largest possible arguments that will be passed
	23	'\" to .AP later. If args are omitted, default tab stops are used.
	24	'\"
	25	'\" .BS
	26	'\" Start box enclosure. From here until next .BE, everything will be
	27	'\" enclosed in one large box.
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	43	'\" is present, then a line break is forced before starting the sidebar.
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245	..
246	.TH Tcl_DoOneEvent 3 7.5 Tcl "Tcl Library Procedures"
247	.BS
248	.SH NAME
249	Tcl_DoOneEvent \- wait for events and invoke event handlers
250	.SH SYNOPSIS
251	.nf
252	\fB#include <tcl.h>\fR
253	.sp
254	int
255	\fBTcl_DoOneEvent\fR(\fIflags\fR)
256	.SH ARGUMENTS
257	.AS int flags
258	.AP int flags in
259	This parameter is normally zero. It may be an OR-ed combination
260	of any of the following flag bits:
261	TCL_WINDOW_EVENTS,
262	TCL_FILE_EVENTS, TCL_TIMER_EVENTS, TCL_IDLE_EVENTS, TCL_ALL_EVENTS, or
263	TCL_DONT_WAIT.
264	.BE
265
266	.SH DESCRIPTION
267	.PP
268	This procedure is the entry point to Tcl's event loop; it is responsible for
269	waiting for events and dispatching event handlers created with
270	procedures such as \fBTk_CreateEventHandler\fR, \fBTcl_CreateFileHandler\fR,
271	\fBTcl_CreateTimerHandler\fR, and \fBTcl_DoWhenIdle\fR.
272	\fBTcl_DoOneEvent\fR checks to see if
273	events are already present on the Tcl event queue; if so,
274	it calls the handler(s) for the first (oldest) event, removes it from
275	the queue, and returns.
276	If there are no events ready to be handled, then \fBTcl_DoOneEvent\fR
277	checks for new events from all possible sources.
278	If any are found, it puts all of them on Tcl's event queue, calls
279	handlers for the first event on the queue, and returns.
280	If no events are found, \fBTcl_DoOneEvent\fR checks for \fBTcl_DoWhenIdle\fR
281	callbacks; if any are found, it invokes all of them and returns.
282	Finally, if no events or idle callbacks have been found, then
283	\fBTcl_DoOneEvent\fR sleeps until an event occurs; then it adds any
284	new events to the Tcl event queue, calls handlers for the first event,
285	and returns.
286	The normal return value is 1 to signify that some event
287	was processed (see below for other alternatives).
288	.PP
289	If the \fIflags\fR argument to \fBTcl_DoOneEvent\fR is non-zero,
290	it restricts the kinds of events that will be processed by
291	\fBTcl_DoOneEvent\fR.
292	\fIFlags\fR may be an OR-ed combination of any of the following bits:
293	.TP 27
294	\fBTCL_WINDOW_EVENTS\fR \-
295	Process window system events.
296	.TP 27
297	\fBTCL_FILE_EVENTS\fR \-
298	Process file events.
299	.TP 27
300	\fBTCL_TIMER_EVENTS\fR \-
301	Process timer events.
302	.TP 27
303	\fBTCL_IDLE_EVENTS\fR \-
304	Process idle callbacks.
305	.TP 27
306	\fBTCL_ALL_EVENTS\fR \-
307	Process all kinds of events: equivalent to OR-ing together all of the
308	above flags or specifying none of them.
309	.TP 27
310	\fBTCL_DONT_WAIT\fR \-
311	Don't sleep: process only events that are ready at the time of the
312	call.
313	.LP
314	If any of the flags \fBTCL_WINDOW_EVENTS\fR, \fBTCL_FILE_EVENTS\fR,
315	\fBTCL_TIMER_EVENTS\fR, or \fBTCL_IDLE_EVENTS\fR is set, then the only
316	events that will be considered are those for which flags are set.
317	Setting none of these flags is equivalent to the value
318	\fBTCL_ALL_EVENTS\fR, which causes all event types to be processed.
319	If an application has defined additional event sources with
320	\fBTcl_CreateEventSource\fR, then additional \fIflag\fR values
321	may also be valid, depending on those event sources.
322	.PP
323	The \fBTCL_DONT_WAIT\fR flag causes \fBTcl_DoOneEvent\fR not to put
324	the process to sleep: it will check for events but if none are found
325	then it returns immediately with a return value of 0 to indicate
326	that no work was done.
327	\fBTcl_DoOneEvent\fR will also return 0 without doing anything if
328	the only alternative is to block forever (this can happen, for example,
329	if \fIflags\fR is \fBTCL_IDLE_EVENTS\fR and there are no
330	\fBTcl_DoWhenIdle\fR callbacks pending, or if no event handlers or
331	timer handlers exist).
332	.PP
333	\fBTcl_DoOneEvent\fR may be invoked recursively. For example,
334	it is possible to invoke \fBTcl_DoOneEvent\fR recursively
335	from a handler called by \fBTcl_DoOneEvent\fR. This sort
336	of operation is useful in some modal situations, such
337	as when a
338	notification dialog has been popped up and an application wishes to
339	wait for the user to click a button in the dialog before
340	doing anything else.
341
342	.SH KEYWORDS
343	callback, event, handler, idle, timer