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

'\"
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'\" RCS: @(#) $Id: CrtFileHdlr.3,v 1.2 1998/09/14 18:39:47 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,
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'\"	needed;  use .AS below instead)
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'\"	name are examples of largest possible arguments that will be passed
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'\"	options follow on successive lines, in four columns separated
'\"	by tabs.
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'\"	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
'\"	the option's name in the option database, and dbClass gives
'\"	the option's class in the option database.
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.AS Tcl_Interp Tcl_CreateInterp in/out
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See the \\fBoptions\\fR manual entry for details on the standard options.
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.TH Tcl_CreateFileHandler 3 8.0 Tcl "Tcl Library Procedures"
.BS
.SH NAME
Tcl_CreateFileHandler, Tcl_DeleteFileHandler \- associate procedure callbacks with files or devices (Unix only)
.SH SYNOPSIS
.nf
\fB#include <tcl.h>\fR
.VS
.sp
\fBTcl_CreateFileHandler\fR(\fIfd, mask, proc, clientData\fR)
.sp
\fBTcl_DeleteFileHandler\fR(\fIfd\fR)
.VE
.SH ARGUMENTS
.AS Tcl_FileProc clientData
.VS
.AP int fd in
Unix file descriptor for an open file or device.
.VE
.AP int mask in
Conditions under which \fIproc\fR should be called:
OR-ed combination of \fBTCL_READABLE\fR, \fBTCL_WRITABLE\fR,
and \fBTCL_EXCEPTION\fR.  May be set to 0 to temporarily disable
a handler.
.AP Tcl_FileProc *proc in
Procedure to invoke whenever the file or device indicated
by \fIfile\fR meets the conditions specified by \fImask\fR.
.AP ClientData clientData in
Arbitrary one-word value to pass to \fIproc\fR.
.BE

.SH DESCRIPTION
.PP
.VS
\fBTcl_CreateFileHandler\fR arranges for \fIproc\fR to be
invoked in the future whenever I/O becomes possible on a file
or an exceptional condition exists for the file.  The file
is indicated by \fIfd\fR, and the conditions of interest
.VE
are indicated by \fImask\fR.  For example, if \fImask\fR
is \fBTCL_READABLE\fR, \fIproc\fR will be called when
the file is readable.
The callback to \fIproc\fR is made by \fBTcl_DoOneEvent\fR, so
\fBTcl_CreateFileHandler\fR is only useful in programs that dispatch
events through \fBTcl_DoOneEvent\fR or through Tcl commands such
as \fBvwait\fR.
.PP
\fIProc\fR should have arguments and result that match the
type \fBTcl_FileProc\fR:
.CS
typedef void Tcl_FileProc(
	ClientData \fIclientData\fR,
	int \fImask\fR);
.CE
The \fIclientData\fR parameter to \fIproc\fR is a copy
of the \fIclientData\fR
argument given to \fBTcl_CreateFileHandler\fR when the callback
was created.  Typically, \fIclientData\fR points to a data
structure containing application-specific information about
the file.  \fIMask\fR is an integer mask indicating which
of the requested conditions actually exists for the file;  it
will contain a subset of the bits in the \fImask\fR argument
to \fBTcl_CreateFileHandler\fR.
.PP
.PP
There may exist only one handler for a given file at a given time.
If \fBTcl_CreateFileHandler\fR is called when a handler already
exists for \fIfd\fR, then the new callback replaces the information
that was previously recorded.
.PP
\fBTcl_DeleteFileHandler\fR may be called to delete the
file handler for \fIfd\fR;  if no handler exists for the
file given by \fIfd\fR then the procedure has no effect.
.PP
The purpose of file handlers is to enable an application to respond to
events while waiting for files to become ready for I/O.  For this to work
correctly, the application may need to use non-blocking I/O operations on
the files for which handlers are declared.  Otherwise the application may
block if it reads or writes too much data; while waiting for the I/O to
complete the application won't be able to service other events. Use
\fBTcl_SetChannelOption\fR with \fB\-blocking\fR to set the channel into
blocking or nonblocking mode as required.
.PP
.VS
Note that these interfaces are only supported by the Unix
implementation of the Tcl notifier.   
.VE

.SH KEYWORDS
callback, file, handler
Commit	Line	Data
920dae64 AT	1	'\"
	2	'\" Copyright (c) 1990-1994 The Regents of the University of California.
	3	'\" Copyright (c) 1994-1997 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: CrtFileHdlr.3,v 1.2 1998/09/14 18:39:47 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	'\"
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	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)
87	.\".b
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105	.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
106	.nr )C \\n()Bu+\\w'(in/out)'u+2n
107	..
108	.AS Tcl_Interp Tcl_CreateInterp in/out
109	'\" # BS - start boxed text
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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'
135	.\}
136	.\}
137	.fi
138	.br
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162	.\}
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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	.\}
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180	.nr ^x \\n(^tu+1v-\\n(^Yu
181	\kx\h'-\\nxu'\h'\|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'\|0u'\c
182	.\}
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205	..
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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	..
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222	.de OP
223	.LP
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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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242	..
243	.de UL
244	\\$1\l'\|0\(ul'\\$2
245	..
246	.TH Tcl_CreateFileHandler 3 8.0 Tcl "Tcl Library Procedures"
247	.BS
248	.SH NAME
249	Tcl_CreateFileHandler, Tcl_DeleteFileHandler \- associate procedure callbacks with files or devices (Unix only)
250	.SH SYNOPSIS
251	.nf
252	\fB#include <tcl.h>\fR
253	.VS
254	.sp
255	\fBTcl_CreateFileHandler\fR(\fIfd, mask, proc, clientData\fR)
256	.sp
257	\fBTcl_DeleteFileHandler\fR(\fIfd\fR)
258	.VE
259	.SH ARGUMENTS
260	.AS Tcl_FileProc clientData
261	.VS
262	.AP int fd in
263	Unix file descriptor for an open file or device.
264	.VE
265	.AP int mask in
266	Conditions under which \fIproc\fR should be called:
267	OR-ed combination of \fBTCL_READABLE\fR, \fBTCL_WRITABLE\fR,
268	and \fBTCL_EXCEPTION\fR. May be set to 0 to temporarily disable
269	a handler.
270	.AP Tcl_FileProc *proc in
271	Procedure to invoke whenever the file or device indicated
272	by \fIfile\fR meets the conditions specified by \fImask\fR.
273	.AP ClientData clientData in
274	Arbitrary one-word value to pass to \fIproc\fR.
275	.BE
276
277	.SH DESCRIPTION
278	.PP
279	.VS
280	\fBTcl_CreateFileHandler\fR arranges for \fIproc\fR to be
281	invoked in the future whenever I/O becomes possible on a file
282	or an exceptional condition exists for the file. The file
283	is indicated by \fIfd\fR, and the conditions of interest
284	.VE
285	are indicated by \fImask\fR. For example, if \fImask\fR
286	is \fBTCL_READABLE\fR, \fIproc\fR will be called when
287	the file is readable.
288	The callback to \fIproc\fR is made by \fBTcl_DoOneEvent\fR, so
289	\fBTcl_CreateFileHandler\fR is only useful in programs that dispatch
290	events through \fBTcl_DoOneEvent\fR or through Tcl commands such
291	as \fBvwait\fR.
292	.PP
293	\fIProc\fR should have arguments and result that match the
294	type \fBTcl_FileProc\fR:
295	.CS
296	typedef void Tcl_FileProc(
297	ClientData \fIclientData\fR,
298	int \fImask\fR);
299	.CE
300	The \fIclientData\fR parameter to \fIproc\fR is a copy
301	of the \fIclientData\fR
302	argument given to \fBTcl_CreateFileHandler\fR when the callback
303	was created. Typically, \fIclientData\fR points to a data
304	structure containing application-specific information about
305	the file. \fIMask\fR is an integer mask indicating which
306	of the requested conditions actually exists for the file; it
307	will contain a subset of the bits in the \fImask\fR argument
308	to \fBTcl_CreateFileHandler\fR.
309	.PP
310	.PP
311	There may exist only one handler for a given file at a given time.
312	If \fBTcl_CreateFileHandler\fR is called when a handler already
313	exists for \fIfd\fR, then the new callback replaces the information
314	that was previously recorded.
315	.PP
316	\fBTcl_DeleteFileHandler\fR may be called to delete the
317	file handler for \fIfd\fR; if no handler exists for the
318	file given by \fIfd\fR then the procedure has no effect.
319	.PP
320	The purpose of file handlers is to enable an application to respond to
321	events while waiting for files to become ready for I/O. For this to work
322	correctly, the application may need to use non-blocking I/O operations on
323	the files for which handlers are declared. Otherwise the application may
324	block if it reads or writes too much data; while waiting for the I/O to
325	complete the application won't be able to service other events. Use
326	\fBTcl_SetChannelOption\fR with \fB\-blocking\fR to set the channel into
327	blocking or nonblocking mode as required.
328	.PP
329	.VS
330	Note that these interfaces are only supported by the Unix
331	implementation of the Tcl notifier.
332	.VE
333
334	.SH KEYWORDS
335	callback, file, handler