[OpenSPARC-T2-SAM] / sam-t2 / devtools / v9 / man / man3 / Tcl_DoWhenIdle.3

'\"
'\" Copyright (c) 1990 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
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'\" RCS: @(#) $Id: DoWhenIdle.3,v 1.2 1998/09/14 18:39:48 stanton Exp $
'\" 
'\" The definitions below are for supplemental macros used in Tcl/Tk
'\" manual entries.
'\"
'\" .AP type name in/out ?indent?
'\"	Start paragraph describing an argument to a library procedure.
'\"	type is type of argument (int, etc.), in/out is either "in", "out",
'\"	or "in/out" to describe whether procedure reads or modifies arg,
'\"	and indent is equivalent to second arg of .IP (shouldn't ever be
'\"	needed;  use .AS below instead)
'\"
'\" .AS ?type? ?name?
'\"	Give maximum sizes of arguments for setting tab stops.  Type and
'\"	name are examples of largest possible arguments that will be passed
'\"	to .AP later.  If args are omitted, default tab stops are used.
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'\"	options follow on successive lines, in four columns separated
'\"	by tabs.
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'\" .SE
'\"	End of list of standard options for a Tk widget.
'\"
'\" .OP cmdName dbName dbClass
'\"	Start of description of a specific option.  cmdName gives the
'\"	option's name as specified in the class command, dbName gives
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'\"	the option's class in the option database.
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'\"	Print arg1 underlined, then print arg2 normally.
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.if t .wh -1.3i ^B
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.SH "STANDARD OPTIONS"
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.LP
See the \\fBoptions\\fR manual entry for details on the standard options.
..
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.de OP
.LP
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Command-Line Name:	\\fB\\$1\\fR
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.TH Tcl_DoWhenIdle 3 7.5 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_DoWhenIdle, Tcl_CancelIdleCall \- invoke a procedure when there are no pending events
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.sp
\fBTcl_DoWhenIdle\fR(\fIproc, clientData\fR)
.sp
\fBTcl_CancelIdleCall\fR(\fIproc, clientData\fR)
.SH ARGUMENTS
.AS Tcl_IdleProc clientData
.AP Tcl_IdleProc *proc in
Procedure to invoke.
.AP ClientData clientData in
Arbitrary one-word value to pass to \fIproc\fR.
.BE

.SH DESCRIPTION
.PP
\fBTcl_DoWhenIdle\fR arranges for \fIproc\fR to be invoked
when the application becomes idle.  The application is
considered to be idle when \fBTcl_DoOneEvent\fR has been
called, couldn't find any events to handle, and is about
to go to sleep waiting for an event to occur.  At this
point all pending \fBTcl_DoWhenIdle\fR handlers are
invoked.  For each call to \fBTcl_DoWhenIdle\fR there will
be a single call to \fIproc\fR;  after \fIproc\fR is
invoked the handler is automatically removed.
\fBTcl_DoWhenIdle\fR is only usable in programs that
use \fBTcl_DoOneEvent\fR to dispatch events.
.PP
\fIProc\fR should have arguments and result that match the
type \fBTcl_IdleProc\fR:
.CS
typedef void Tcl_IdleProc(ClientData \fIclientData\fR);
.CE
The \fIclientData\fR parameter to \fIproc\fR is a copy of the \fIclientData\fR
argument given to \fBTcl_DoWhenIdle\fR.  Typically, \fIclientData\fR
points to a data structure containing application-specific information about
what \fIproc\fR should do.
.PP
\fBTcl_CancelIdleCall\fR
may be used to cancel one or more previous
calls to \fBTcl_DoWhenIdle\fR:  if there is a \fBTcl_DoWhenIdle\fR
handler registered for \fIproc\fR and \fIclientData\fR, then it
is removed without invoking it.  If there is more than one
handler on the idle list that refers to \fIproc\fR and \fIclientData\fR,
all of the handlers are removed.  If no existing handlers match
\fIproc\fR and \fIclientData\fR then nothing happens.
.PP
\fBTcl_DoWhenIdle\fR is most useful in situations where
(a) a piece of work will have to be done but (b) it's
possible that something will happen in the near future
that will change what has to be done or require something
different to be done.  \fBTcl_DoWhenIdle\fR allows the
actual work to be deferred until all pending events have
been processed.  At this point the exact work to be done
will presumably be known and it can be done exactly once.
.PP
For example, \fBTcl_DoWhenIdle\fR might be used by an editor
to defer display updates until all pending commands have
been processed.  Without this feature, redundant redisplays
might occur in some situations, such as the processing of
a command file.
.SH BUGS
.PP
At present it is not safe for an idle callback to reschedule itself
continuously.  This will interact badly with certain features of Tk
that attempt to wait for all idle callbacks to complete.  If you would
like for an idle callback to reschedule itself continuously, it is
better to use a timer handler with a zero timeout period.

.SH KEYWORDS
callback, defer, idle callback
Commit	Line	Data
920dae64 AT	1	'\"
	2	'\" Copyright (c) 1990 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: DoWhenIdle.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.
	28	'\"
	29	'\" .BE
	30	'\" End of box enclosure.
	31	'\"
	32	'\" .CS
	33	'\" Begin code excerpt.
	34	'\"
	35	'\" .CE
	36	'\" End code excerpt.
	37	'\"
	38	'\" .VS ?version? ?br?
	39	'\" Begin vertical sidebar, for use in marking newly-changed parts
	40	'\" of man pages. The first argument is ignored and used for recording
	41	'\" the version when the .VS was added, so that the sidebars can be
	42	'\" found and removed when they reach a certain age. If another argument
	43	'\" is present, then a line break is forced before starting the sidebar.
	44	'\"
	45	'\" .VE
	46	'\" End of vertical sidebar.
	47	'\"
	48	'\" .DS
	49	'\" Begin an indented unfilled display.
	50	'\"
	51	'\" .DE
	52	'\" End of indented unfilled display.
	53	'\"
	54	'\" .SO
	55	'\" Start of list of standard options for a Tk widget. The
	56	'\" options follow on successive lines, in four columns separated
	57	'\" by tabs.
	58	'\"
	59	'\" .SE
	60	'\" End of list of standard options for a Tk widget.
	61	'\"
	62	'\" .OP cmdName dbName dbClass
	63	'\" Start of description of a specific option. cmdName gives the
	64	'\" option's name as specified in the class command, dbName gives
65	'\" the option's name in the option database, and dbClass gives
66	'\" the option's class in the option database.
67	'\"
68	'\" .UL arg1 arg2
69	'\" Print arg1 underlined, then print arg2 normally.
70	'\"
71	'\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
72	'\"
73	'\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
74	.if t .wh -1.3i ^B
75	.nr ^l \n(.l
76	.ad b
77	'\" # Start an argument description
78	.de AP
79	.ie !"\\$4"" .TP \\$4
80	.el \{\
81	. ie !"\\$2"" .TP \\n()Cu
82	. el .TP 15
83	.\}
84	.ta \\n()Au \\n()Bu
85	.ie !"\\$3"" \{\
86	\&\\$1 \\fI\\$2\\fP (\\$3)
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106	.nr )C \\n()Bu+\\w'(in/out)'u+2n
107	..
108	.AS Tcl_Interp Tcl_CreateInterp in/out
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129	.\" box if the box started on an earlier page.
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131	\h'-1.5n'\L'\|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'\|0u-1.5n\(ul'
132	.\}
133	.el \}\
134	\h'-1.5n'\L'\|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'\|0u-1.5n\(ul'
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175	.\" draw two sides but no top otherwise.
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177	.el \h'-1.5n'\L'\|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'\|0u'\c
178	.\}
179	.if \\n(^v \{\
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181	\kx\h'-\\nxu'\h'\|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'\|0u'\c
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204	.sp
205	..
206	'\" # SO - start of list of standard options
207	.de SO
208	.SH "STANDARD OPTIONS"
209	.LP
210	.nf
211	.ta 5.5c 11c
212	.ft B
213	..
214	'\" # SE - end of list of standard options
215	.de SE
216	.fi
217	.ft R
218	.LP
219	See the \\fBoptions\\fR manual entry for details on the standard options.
220	..
221	'\" # OP - start of full description for a single option
222	.de OP
223	.LP
224	.nf
225	.ta 4c
226	Command-Line Name: \\fB\\$1\\fR
227	Database Name: \\fB\\$2\\fR
228	Database Class: \\fB\\$3\\fR
229	.fi
230	.IP
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240	.fi
241	.RE
242	..
243	.de UL
244	\\$1\l'\|0\(ul'\\$2
245	..
246	.TH Tcl_DoWhenIdle 3 7.5 Tcl "Tcl Library Procedures"
247	.BS
248	.SH NAME
249	Tcl_DoWhenIdle, Tcl_CancelIdleCall \- invoke a procedure when there are no pending events
250	.SH SYNOPSIS
251	.nf
252	\fB#include <tcl.h>\fR
253	.sp
254	\fBTcl_DoWhenIdle\fR(\fIproc, clientData\fR)
255	.sp
256	\fBTcl_CancelIdleCall\fR(\fIproc, clientData\fR)
257	.SH ARGUMENTS
258	.AS Tcl_IdleProc clientData
259	.AP Tcl_IdleProc *proc in
260	Procedure to invoke.
261	.AP ClientData clientData in
262	Arbitrary one-word value to pass to \fIproc\fR.
263	.BE
264
265	.SH DESCRIPTION
266	.PP
267	\fBTcl_DoWhenIdle\fR arranges for \fIproc\fR to be invoked
268	when the application becomes idle. The application is
269	considered to be idle when \fBTcl_DoOneEvent\fR has been
270	called, couldn't find any events to handle, and is about
271	to go to sleep waiting for an event to occur. At this
272	point all pending \fBTcl_DoWhenIdle\fR handlers are
273	invoked. For each call to \fBTcl_DoWhenIdle\fR there will
274	be a single call to \fIproc\fR; after \fIproc\fR is
275	invoked the handler is automatically removed.
276	\fBTcl_DoWhenIdle\fR is only usable in programs that
277	use \fBTcl_DoOneEvent\fR to dispatch events.
278	.PP
279	\fIProc\fR should have arguments and result that match the
280	type \fBTcl_IdleProc\fR:
281	.CS
282	typedef void Tcl_IdleProc(ClientData \fIclientData\fR);
283	.CE
284	The \fIclientData\fR parameter to \fIproc\fR is a copy of the \fIclientData\fR
285	argument given to \fBTcl_DoWhenIdle\fR. Typically, \fIclientData\fR
286	points to a data structure containing application-specific information about
287	what \fIproc\fR should do.
288	.PP
289	\fBTcl_CancelIdleCall\fR
290	may be used to cancel one or more previous
291	calls to \fBTcl_DoWhenIdle\fR: if there is a \fBTcl_DoWhenIdle\fR
292	handler registered for \fIproc\fR and \fIclientData\fR, then it
293	is removed without invoking it. If there is more than one
294	handler on the idle list that refers to \fIproc\fR and \fIclientData\fR,
295	all of the handlers are removed. If no existing handlers match
296	\fIproc\fR and \fIclientData\fR then nothing happens.
297	.PP
298	\fBTcl_DoWhenIdle\fR is most useful in situations where
299	(a) a piece of work will have to be done but (b) it's
300	possible that something will happen in the near future
301	that will change what has to be done or require something
302	different to be done. \fBTcl_DoWhenIdle\fR allows the
303	actual work to be deferred until all pending events have
304	been processed. At this point the exact work to be done
305	will presumably be known and it can be done exactly once.
306	.PP
307	For example, \fBTcl_DoWhenIdle\fR might be used by an editor
308	to defer display updates until all pending commands have
309	been processed. Without this feature, redundant redisplays
310	might occur in some situations, such as the processing of
311	a command file.
312	.SH BUGS
313	.PP
314	At present it is not safe for an idle callback to reschedule itself
315	continuously. This will interact badly with certain features of Tk
316	that attempt to wait for all idle callbacks to complete. If you would
317	like for an idle callback to reschedule itself continuously, it is
318	better to use a timer handler with a zero timeout period.
319
320	.SH KEYWORDS
321	callback, defer, idle callback