| '\" |
| '\" Copyright (c) 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. |
| '\" |
| '\" RCS: @(#) $Id: CrtChnlHdlr.3,v 1.2 1998/09/14 18:39:46 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. |
| '\" |
| '\" .BS |
| '\" Start box enclosure. From here until next .BE, everything will be |
| '\" enclosed in one large box. |
| '\" |
| '\" .BE |
| '\" End of box enclosure. |
| '\" |
| '\" .CS |
| '\" Begin code excerpt. |
| '\" |
| '\" .CE |
| '\" End code excerpt. |
| '\" |
| '\" .VS ?version? ?br? |
| '\" Begin vertical sidebar, for use in marking newly-changed parts |
| '\" of man pages. The first argument is ignored and used for recording |
| '\" the version when the .VS was added, so that the sidebars can be |
| '\" found and removed when they reach a certain age. If another argument |
| '\" is present, then a line break is forced before starting the sidebar. |
| '\" |
| '\" .VE |
| '\" End of vertical sidebar. |
| '\" |
| '\" .DS |
| '\" Begin an indented unfilled display. |
| '\" |
| '\" .DE |
| '\" End of indented unfilled display. |
| '\" |
| '\" .SO |
| '\" Start of list of standard options for a Tk widget. The |
| '\" options follow on successive lines, in four columns separated |
| '\" by tabs. |
| '\" |
| '\" .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 |
| '\" the option's name in the option database, and dbClass gives |
| '\" the option's class in the option database. |
| '\" |
| '\" .UL arg1 arg2 |
| '\" Print arg1 underlined, then print arg2 normally. |
| '\" |
| '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $ |
| '\" |
| '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. |
| .if t .wh -1.3i ^B |
| .nr ^l \n(.l |
| .ad b |
| '\" # Start an argument description |
| .de AP |
| .ie !"\\$4"" .TP \\$4 |
| .el \{\ |
| . ie !"\\$2"" .TP \\n()Cu |
| . el .TP 15 |
| .\} |
| .ta \\n()Au \\n()Bu |
| .ie !"\\$3"" \{\ |
| \&\\$1 \\fI\\$2\\fP (\\$3) |
| .\".b |
| .\} |
| .el \{\ |
| .br |
| .ie !"\\$2"" \{\ |
| \&\\$1 \\fI\\$2\\fP |
| .\} |
| .el \{\ |
| \&\\fI\\$1\\fP |
| .\} |
| .\} |
| .. |
| '\" # define tabbing values for .AP |
| .de AS |
| .nr )A 10n |
| .if !"\\$1"" .nr )A \\w'\\$1'u+3n |
| .nr )B \\n()Au+15n |
| .\" |
| .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n |
| .nr )C \\n()Bu+\\w'(in/out)'u+2n |
| .. |
| .AS Tcl_Interp Tcl_CreateInterp in/out |
| '\" # BS - start boxed text |
| '\" # ^y = starting y location |
| '\" # ^b = 1 |
| .de BS |
| .br |
| .mk ^y |
| .nr ^b 1u |
| .if n .nf |
| .if n .ti 0 |
| .if n \l'\\n(.lu\(ul' |
| .if n .fi |
| .. |
| '\" # BE - end boxed text (draw box now) |
| .de BE |
| .nf |
| .ti 0 |
| .mk ^t |
| .ie n \l'\\n(^lu\(ul' |
| .el \{\ |
| .\" Draw four-sided box normally, but don't draw top of |
| .\" box if the box started on an earlier page. |
| .ie !\\n(^b-1 \{\ |
| \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| .\} |
| .el \}\ |
| \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' |
| .\} |
| .\} |
| .fi |
| .br |
| .nr ^b 0 |
| .. |
| '\" # VS - start vertical sidebar |
| '\" # ^Y = starting y location |
| '\" # ^v = 1 (for troff; for nroff this doesn't matter) |
| .de VS |
| .if !"\\$2"" .br |
| .mk ^Y |
| .ie n 'mc \s12\(br\s0 |
| .el .nr ^v 1u |
| .. |
| '\" # VE - end of vertical sidebar |
| .de VE |
| .ie n 'mc |
| .el \{\ |
| .ev 2 |
| .nf |
| .ti 0 |
| .mk ^t |
| \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' |
| .sp -1 |
| .fi |
| .ev |
| .\} |
| .nr ^v 0 |
| .. |
| '\" # Special macro to handle page bottom: finish off current |
| '\" # box/sidebar if in box/sidebar mode, then invoked standard |
| '\" # page bottom macro. |
| .de ^B |
| .ev 2 |
| 'ti 0 |
| 'nf |
| .mk ^t |
| .if \\n(^b \{\ |
| .\" Draw three-sided box if this is the box's first page, |
| .\" draw two sides but no top otherwise. |
| .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 |
| .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c |
| .\} |
| .if \\n(^v \{\ |
| .nr ^x \\n(^tu+1v-\\n(^Yu |
| \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c |
| .\} |
| .bp |
| 'fi |
| .ev |
| .if \\n(^b \{\ |
| .mk ^y |
| .nr ^b 2 |
| .\} |
| .if \\n(^v \{\ |
| .mk ^Y |
| .\} |
| .. |
| '\" # DS - begin display |
| .de DS |
| .RS |
| .nf |
| .sp |
| .. |
| '\" # DE - end display |
| .de DE |
| .fi |
| .RE |
| .sp |
| .. |
| '\" # SO - start of list of standard options |
| .de SO |
| .SH "STANDARD OPTIONS" |
| .LP |
| .nf |
| .ta 5.5c 11c |
| .ft B |
| .. |
| '\" # SE - end of list of standard options |
| .de SE |
| .fi |
| .ft R |
| .LP |
| See the \\fBoptions\\fR manual entry for details on the standard options. |
| .. |
| '\" # OP - start of full description for a single option |
| .de OP |
| .LP |
| .nf |
| .ta 4c |
| Command-Line Name: \\fB\\$1\\fR |
| Database Name: \\fB\\$2\\fR |
| Database Class: \\fB\\$3\\fR |
| .fi |
| .IP |
| .. |
| '\" # CS - begin code excerpt |
| .de CS |
| .RS |
| .nf |
| .ta .25i .5i .75i 1i |
| .. |
| '\" # CE - end code excerpt |
| .de CE |
| .fi |
| .RE |
| .. |
| .de UL |
| \\$1\l'|0\(ul'\\$2 |
| .. |
| .TH Tcl_CreateChannelHandler 3 7.5 Tcl "Tcl Library Procedures" |
| .BS |
| '\" Note: do not modify the .SH NAME line immediately below! |
| .SH NAME |
| Tcl_CreateChannelHandler, Tcl_DeleteChannelHandler \- call a procedure when a channel becomes readable or writable |
| .SH SYNOPSIS |
| .nf |
| .nf |
| \fB#include <tcl.h>\fR |
| .sp |
| void |
| \fBTcl_CreateChannelHandler\fR(\fIchannel, mask, proc, clientData\fR) |
| .sp |
| void |
| \fBTcl_DeleteChannelHandler\fR(\fIchannel, proc, clientData\fR) |
| .sp |
| .SH ARGUMENTS |
| .AS Tcl_ChannelProc clientData |
| .AP Tcl_Channel channel in |
| Tcl channel such as returned by \fBTcl_CreateChannel\fR. |
| .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. Specify |
| a zero value to temporarily disable an existing handler. |
| .AP Tcl_FileProc *proc in |
| Procedure to invoke whenever the channel indicated by \fIchannel\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 |
| \fBTcl_CreateChannelHandler\fR arranges for \fIproc\fR to be called in the |
| future whenever input or output becomes possible on the channel identified |
| by \fIchannel\fR, or whenever an exceptional condition exists for |
| \fIchannel\fR. The conditions of interest under which \fIproc\fR will be |
| invoked are specified by the \fImask\fR argument. |
| See the manual entry for \fBfileevent\fR for a precise description of |
| what it means for a channel to be readable or writable. |
| \fIProc\fR must conform to the following prototype: |
| .CS |
| typedef void Tcl_ChannelProc( |
| ClientData \fIclientData\fR, |
| int \fImask\fR); |
| .CE |
| .PP |
| The \fIclientData\fR argument is the same as the value passed to |
| \fBTcl_CreateChannelHandler\fR when the handler was created. Typically, |
| \fIclientData\fR points to a data structure containing application-specific |
| information about the channel. \fIMask\fR is an integer mask indicating |
| which of the requested conditions actually exists for the channel; it will |
| contain a subset of the bits from the \fImask\fR argument to |
| \fBTcl_CreateChannelHandler\fR when the handler was created. |
| .PP |
| Each channel handler is identified by a unique combination of \fIchannel\fR, |
| \fIproc\fR and \fIclientData\fR. |
| There may be many handlers for a given channel as long as they don't |
| have the same \fIchannel\fR, \fIproc\fR, and \fIclientData\fR. |
| If \fBTcl_CreateChannelHandler\fR is invoked when there is already a handler |
| for \fIchannel\fR, \fIproc\fR, and \fIclientData\fR, then no new |
| handler is created; instead, the \fImask\fR is changed for the |
| existing handler. |
| .PP |
| \fBTcl_DeleteChannelHandler\fR deletes a channel handler identified by |
| \fIchannel\fR, \fIproc\fR and \fIclientData\fR; if no such handler exists, |
| the call has no effect. |
| .PP |
| Channel handlers are invoked via the Tcl event mechanism, so they |
| are only useful in applications that are event-driven. |
| Note also that the conditions specified in the \fImask\fR argument |
| to \fIproc\fR may no longer exist when \fIproc\fR is invoked: for |
| example, if there are two handlers for \fBTCL_READABLE\fR on the same |
| channel, the first handler could consume all of the available input |
| so that the channel is no longer readable when the second handler |
| is invoked. |
| For this reason it may be useful to use nonblocking I/O on channels |
| for which there are event handlers. |
| |
| .SH "SEE ALSO" |
| Notifier(3), Tcl_CreateChannel(3), Tcl_OpenFileChannel(3), vwait(n). |
| |
| .SH KEYWORDS |
| blocking, callback, channel, events, handler, nonblocking. |