2 '\" Copyright (c) 1996 Sun Microsystems, Inc.
4 '\" See the file "license.terms" for information on usage and redistribution
5 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
7 .TH Tcl_CreateChannelHandler 3 7.5 Tcl "Tcl Library Procedures"
8 .\" The -*- nroff -*- definitions below are for supplemental macros used
9 .\" in Tcl/Tk manual entries.
11 .\" .AP type name in/out ?indent?
12 .\" Start paragraph describing an argument to a library procedure.
13 .\" type is type of argument (int, etc.), in/out is either "in", "out",
14 .\" or "in/out" to describe whether procedure reads or modifies arg,
15 .\" and indent is equivalent to second arg of .IP (shouldn't ever be
16 .\" needed; use .AS below instead)
19 .\" Give maximum sizes of arguments for setting tab stops. Type and
20 .\" name are examples of largest possible arguments that will be passed
21 .\" to .AP later. If args are omitted, default tab stops are used.
24 .\" Start box enclosure. From here until next .BE, everything will be
25 .\" enclosed in one large box.
28 .\" End of box enclosure.
31 .\" Begin code excerpt.
36 .\" .VS ?version? ?br?
37 .\" Begin vertical sidebar, for use in marking newly-changed parts
38 .\" of man pages. The first argument is ignored and used for recording
39 .\" the version when the .VS was added, so that the sidebars can be
40 .\" found and removed when they reach a certain age. If another argument
41 .\" is present, then a line break is forced before starting the sidebar.
44 .\" End of vertical sidebar.
47 .\" Begin an indented unfilled display.
50 .\" End of indented unfilled display.
53 .\" Start of list of standard options for a Tk widget. The manpage
54 .\" argument defines where to look up the standard options; if
55 .\" omitted, defaults to "options". The options follow on successive
56 .\" lines, in three columns separated by tabs.
59 .\" End of list of standard options for a Tk widget.
61 .\" .OP cmdName dbName dbClass
62 .\" Start of description of a specific option. cmdName gives the
63 .\" option's name as specified in the class command, dbName gives
64 .\" the option's name in the option database, and dbClass gives
65 .\" the option's class in the option database.
68 .\" Print arg1 underlined, then print arg2 normally.
71 .\" Print arg1 in quotes, then arg2 normally (for trailing punctuation).
74 .\" Print an open parenthesis, arg1 in quotes, then arg2 normally
75 .\" (for trailing punctuation) and then a closing parenthesis.
77 .\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
81 .\" # Start an argument description
85 . ie !"\\$2"" .TP \\n()Cu
90 \&\\$1 \\fI\\$2\\fP (\\$3)
103 .\" # define tabbing values for .AP
106 .if !"\\$1"" .nr )A \\w'\\$1'u+3n
109 .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
110 .nr )C \\n()Bu+\\w'(in/out)'u+2n
112 .AS Tcl_Interp Tcl_CreateInterp in/out
113 .\" # BS - start boxed text
114 .\" # ^y = starting y location
122 .if n \l'\\n(.lu\(ul'
125 .\" # BE - end boxed text (draw box now)
130 .ie n \l'\\n(^lu\(ul'
132 .\" Draw four-sided box normally, but don't draw top of
133 .\" box if the box started on an earlier page.
135 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
138 \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
145 .\" # VS - start vertical sidebar
146 .\" # ^Y = starting y location
147 .\" # ^v = 1 (for troff; for nroff this doesn't matter)
151 .ie n 'mc \s12\(br\s0
154 .\" # VE - end of vertical sidebar
162 \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
169 .\" # Special macro to handle page bottom: finish off current
170 .\" # box/sidebar if in box/sidebar mode, then invoked standard
171 .\" # page bottom macro.
178 .\" Draw three-sided box if this is the box's first page,
179 .\" draw two sides but no top otherwise.
180 .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
181 .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
184 .nr ^x \\n(^tu+1v-\\n(^Yu
185 \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
198 .\" # DS - begin display
204 .\" # DE - end display
210 .\" # SO - start of list of standard options
212 'ie '\\$1'' .ds So \\fBoptions\\fR
213 'el .ds So \\fB\\$1\\fR
214 .SH "STANDARD OPTIONS"
220 .\" # SE - end of list of standard options
225 See the \\*(So manual entry for details on the standard options.
227 .\" # OP - start of full description for a single option
232 Command-Line Name: \\fB\\$1\\fR
233 Database Name: \\fB\\$2\\fR
234 Database Class: \\fB\\$3\\fR
238 .\" # CS - begin code excerpt
244 .\" # CE - end code excerpt
249 .\" # UL - underline word
253 .\" # QW - apply quotation marks to word
255 .ie '\\*(lq'"' ``\\$1''\\$2
256 .\"" fix emacs highlighting
257 .el \\*(lq\\$1\\*(rq\\$2
259 .\" # PQ - apply parens and quotation marks to word
261 .ie '\\*(lq'"' (``\\$1''\\$2)\\$3
262 .\"" fix emacs highlighting
263 .el (\\*(lq\\$1\\*(rq\\$2)\\$3
265 .\" # QR - quoted range
267 .ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
268 .\"" fix emacs highlighting
269 .el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
271 .\" # MT - "empty" string
276 '\" Note: do not modify the .SH NAME line immediately below!
278 Tcl_CreateChannelHandler, Tcl_DeleteChannelHandler \- call a procedure when a channel becomes readable or writable
282 \fB#include <tcl.h>\fR
285 \fBTcl_CreateChannelHandler\fR(\fIchannel, mask, proc, clientData\fR)
288 \fBTcl_DeleteChannelHandler\fR(\fIchannel, proc, clientData\fR)
291 .AS Tcl_ChannelProc clientData
292 .AP Tcl_Channel channel in
293 Tcl channel such as returned by \fBTcl_CreateChannel\fR.
295 Conditions under which \fIproc\fR should be called: OR-ed combination of
296 \fBTCL_READABLE\fR, \fBTCL_WRITABLE\fR and \fBTCL_EXCEPTION\fR. Specify
297 a zero value to temporarily disable an existing handler.
298 .AP Tcl_FileProc *proc in
299 Procedure to invoke whenever the channel indicated by \fIchannel\fR meets
300 the conditions specified by \fImask\fR.
301 .AP ClientData clientData in
302 Arbitrary one-word value to pass to \fIproc\fR.
306 \fBTcl_CreateChannelHandler\fR arranges for \fIproc\fR to be called in the
307 future whenever input or output becomes possible on the channel identified
308 by \fIchannel\fR, or whenever an exceptional condition exists for
309 \fIchannel\fR. The conditions of interest under which \fIproc\fR will be
310 invoked are specified by the \fImask\fR argument.
311 See the manual entry for \fBfileevent\fR for a precise description of
312 what it means for a channel to be readable or writable.
313 \fIProc\fR must conform to the following prototype:
316 typedef void \fBTcl_ChannelProc\fR(
317 ClientData \fIclientData\fR,
321 The \fIclientData\fR argument is the same as the value passed to
322 \fBTcl_CreateChannelHandler\fR when the handler was created. Typically,
323 \fIclientData\fR points to a data structure containing application-specific
324 information about the channel. \fIMask\fR is an integer mask indicating
325 which of the requested conditions actually exists for the channel; it will
326 contain a subset of the bits from the \fImask\fR argument to
327 \fBTcl_CreateChannelHandler\fR when the handler was created.
329 Each channel handler is identified by a unique combination of \fIchannel\fR,
330 \fIproc\fR and \fIclientData\fR.
331 There may be many handlers for a given channel as long as they do not
332 have the same \fIchannel\fR, \fIproc\fR, and \fIclientData\fR.
333 If \fBTcl_CreateChannelHandler\fR is invoked when there is already a handler
334 for \fIchannel\fR, \fIproc\fR, and \fIclientData\fR, then no new
335 handler is created; instead, the \fImask\fR is changed for the
338 \fBTcl_DeleteChannelHandler\fR deletes a channel handler identified by
339 \fIchannel\fR, \fIproc\fR and \fIclientData\fR; if no such handler exists,
340 the call has no effect.
342 Channel handlers are invoked via the Tcl event mechanism, so they
343 are only useful in applications that are event-driven.
344 Note also that the conditions specified in the \fImask\fR argument
345 to \fIproc\fR may no longer exist when \fIproc\fR is invoked: for
346 example, if there are two handlers for \fBTCL_READABLE\fR on the same
347 channel, the first handler could consume all of the available input
348 so that the channel is no longer readable when the second handler
350 For this reason it may be useful to use nonblocking I/O on channels
351 for which there are event handlers.
353 Notifier(3), Tcl_CreateChannel(3), Tcl_OpenFileChannel(3), vwait(n).
355 blocking, callback, channel, events, handler, nonblocking.