| '\" |
| '\" Copyright (c) 1999-2000 Ajuba Solutions. |
| '\" |
| '\" See the file "license.terms" for information on usage and redistribution |
| '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
| '\" |
| '\" RCS: @(#) $Id: ChnlStack.3,v 1.4 2002/01/23 21:22:06 andreas_kupries 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. |
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| '\" .CS |
| '\" Begin code excerpt. |
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| '\" |
| '\" .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. |
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| '\" .SO |
| '\" Start of list of standard options for a Tk widget. The |
| '\" 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. |
| '\" |
| '\" .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 |
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| .el \{\ |
| \&\\fI\\$1\\fP |
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| .\} |
| .. |
| '\" # define tabbing values for .AP |
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| .nr )A 10n |
| .if !"\\$1"" .nr )A \\w'\\$1'u+3n |
| .nr )B \\n()Au+15n |
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| .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 |
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| .br |
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| .if n \l'\\n(.lu\(ul' |
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| .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' |
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| '\" # box/sidebar if in box/sidebar mode, then invoked standard |
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| .\" 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 \{\ |
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| \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c |
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| '\" # 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 |
| .. |
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| .ta .25i .5i .75i 1i |
| .. |
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| .de CE |
| .fi |
| .RE |
| .. |
| .de UL |
| \\$1\l'|0\(ul'\\$2 |
| .. |
| .TH Tcl_StackChannel 3 8.3 Tcl "Tcl Library Procedures" |
| .BS |
| '\" Note: do not modify the .SH NAME line immediately below! |
| .SH NAME |
| Tcl_StackChannel, Tcl_UnstackChannel, Tcl_GetStackedChannel, Tcl_GetTopChannel \- stack an I/O channel on top of another, and undo it |
| .SH SYNOPSIS |
| .nf |
| .nf |
| \fB#include <tcl.h>\fR |
| .sp |
| Tcl_Channel |
| \fBTcl_StackChannel\fR(\fIinterp, typePtr, clientData, mask, channel\fR) |
| .sp |
| int |
| \fBTcl_UnstackChannel\fR(\fIinterp, channel\fR) |
| .sp |
| Tcl_Channel |
| \fBTcl_GetStackedChannel\fR(\fIchannel\fR) |
| .sp |
| Tcl_Channel |
| \fBTcl_GetTopChannel\fR(\fIchannel\fR) |
| .sp |
| .SH ARGUMENTS |
| .AS Tcl_ChannelType |
| .AP Tcl_Interp *interp in |
| Interpreter for error reporting - can be NULL. |
| .AP Tcl_ChannelType *typePtr in |
| The new channel I/O procedures to use for \fIchannel\fP. |
| .AP ClientData clientData in |
| Arbitrary one-word value to pass to channel I/O procedures. |
| .AP int mask in |
| Conditions under which \fIchannel\fR will be used: OR-ed combination of |
| \fBTCL_READABLE\fR, \fBTCL_WRITABLE\fR and \fBTCL_EXCEPTION\fR. |
| This can be a subset of the operations currently allowed on \fIchannel\fP. |
| .AP Tcl_Channel channel in |
| An existing Tcl channel such as returned by \fBTcl_CreateChannel\fR. |
| .BE |
| |
| .SH DESCRIPTION |
| .PP |
| These functions are for use by extensions that add processing layers to Tcl |
| I/O channels. Examples include compression and encryption modules. These |
| functions transparently stack and unstack a new channel on top of an |
| existing one. Any number of channels can be stacked together. |
| .PP |
| The implementation of the Tcl channel code was rewritten in 8.3.2 to |
| correct some problems with the previous implementation with regard to |
| stacked channels. Anyone using stacked channels or creating stacked |
| channel drivers should update to the new \fBTCL_CHANNEL_VERSION_2\fR |
| \fBTcl_ChannelType\fR structure. See \fBTcl_CreateChannel\fR for details. |
| .PP |
| \fBTcl_StackChannel\fR stacks a new \fIchannel\fP on an existing channel |
| with the same name that was registered for \fIchannel\fP by |
| \fBTcl_RegisterChannel\fP. |
| .PP |
| \fBTcl_StackChannel\fR works by creating a new channel structure and |
| placing itself on top of the channel stack. EOL translation, encoding and |
| buffering options are shared between all channels in the stack. The hidden |
| channel does no buffering, newline translations, or character set encoding. |
| Instead, the buffering, newline translations, and encoding functions all |
| remain at the top of the channel stack. A pointer to the new top channel |
| structure is returned. If an error occurs when stacking the channel, NULL |
| is returned instead. |
| .PP |
| The \fImask\fP parameter specifies the operations that are allowed on the |
| new channel. These can be a subset of the operations allowed on the |
| original channel. For example, a read-write channel may become read-only |
| after the \fBTcl_StackChannel\fR call. |
| .PP |
| Closing a channel closes the channels stacked below it. The close of |
| stacked channels is executed in a way that allows buffered data to be |
| properly flushed. |
| .PP |
| \fBTcl_UnstackChannel\fP reverses the process. The old channel is |
| associated with the channel name, and the processing module added by |
| \fBTcl_StackChannel\fR is destroyed. If there is no old channel, then |
| \fBTcl_UnstackChannel\fP is equivalent to \fBTcl_Close\fP. If an error |
| occurs unstacking the channel, \fBTCL_ERROR\fR is returned, otherwise |
| \fBTCL_OK\fR is returned. |
| .PP |
| \fBTcl_GetTopChannel\fR returns the top channel in the stack of |
| channels the supplied channel is part of. |
| .PP |
| \fBTcl_GetStackedChannel\fR returns the channel in the stack of |
| channels which is just below the supplied channel. |
| |
| .SH "SEE ALSO" |
| Notifier(3), Tcl_CreateChannel(3), Tcl_OpenFileChannel(3), vwait(n). |
| |
| .SH KEYWORDS |
| channel, compression |