man/man3/Tcl_GetTopChannel.3 - toolchains/skids - Git at Google

 '\"
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 .AS Tcl_Interp Tcl_CreateInterp in/out
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 .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
	'\"
	'\" 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.
	'\"
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	'\" enclosed in one large box.
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	'\" 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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	'\" 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.
	'\"
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	'\"
	'\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
	.if t .wh -1.3i ^B
	.nr ^l \n(.l
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	'\" # Start an argument description
	.de AP
	.ie !"\\$4"" .TP \\$4
	.el \{\
	. ie !"\\$2"" .TP \\n()Cu
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	.\}
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	\&\\$1 \\fI\\$2\\fP (\\$3)
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	\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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	..
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	Command-Line Name: \\fB\\$1\\fR
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	Database Class: \\fB\\$3\\fR
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	..
	.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