| 1 | '\" |
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| 2 | '\" Copyright (c) 1994 The Regents of the University of California. |
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| 3 | '\" Copyright (c) 1994-1996 Sun Microsystems, Inc. |
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| 4 | '\" |
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| 5 | '\" See the file "license.terms" for information on usage and redistribution |
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| 6 | '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. |
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| 7 | '\" |
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| 8 | '\" RCS: @(#) $Id: UpVar.3,v 1.11 2006/10/09 23:38:56 msofer Exp $ |
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| 9 | '\" |
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| 10 | .so man.macros |
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| 11 | .TH Tcl_UpVar 3 7.4 Tcl "Tcl Library Procedures" |
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| 12 | .BS |
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| 13 | .SH NAME |
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| 14 | Tcl_UpVar, Tcl_UpVar2 \- link one variable to another |
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| 15 | .SH SYNOPSIS |
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| 16 | .nf |
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| 17 | \fB#include <tcl.h>\fR |
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| 18 | .sp |
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| 19 | int |
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| 20 | \fBTcl_UpVar(\fIinterp, frameName, sourceName, destName, flags\fB)\fR |
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| 21 | .sp |
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| 22 | int |
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| 23 | \fBTcl_UpVar2(\fIinterp, frameName, name1, name2, destName, flags\fB)\fR |
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| 24 | .SH ARGUMENTS |
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| 25 | .AS "const char" *sourceName |
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| 26 | .AP Tcl_Interp *interp in |
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| 27 | Interpreter containing variables; also used for error reporting. |
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| 28 | .AP "const char" *frameName in |
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| 29 | Identifies the stack frame containing source variable. |
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| 30 | May have any of the forms accepted by |
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| 31 | the \fBupvar\fR command, such as \fB#0\fR or \fB1\fR. |
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| 32 | .AP "const char" *sourceName in |
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| 33 | Name of source variable, in the frame given by \fIframeName\fR. |
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| 34 | May refer to a scalar variable or to an array variable with a |
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| 35 | parenthesized index. |
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| 36 | .AP "const char" *destName in |
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| 37 | Name of destination variable, which is to be linked to source |
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| 38 | variable so that references to \fIdestName\fR |
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| 39 | refer to the other variable. Must not currently exist except as |
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| 40 | an upvar-ed variable. |
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| 41 | .AP int flags in |
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| 42 | One of \fBTCL_GLOBAL_ONLY\fR, \fBTCL_NAMESPACE_ONLY\fR or 0; if non-zero, |
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| 43 | then \fIdestName\fR is a global or namespace variable; otherwise it is |
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| 44 | local to the current procedure (or current namespace if no procedure is |
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| 45 | active). |
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| 46 | .AP "const char" *name1 in |
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| 47 | First part of source variable's name (scalar name, or name of array |
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| 48 | without array index). |
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| 49 | .AP "const char" *name2 in |
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| 50 | If source variable is an element of an array, gives the index of the element. |
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| 51 | For scalar source variables, is NULL. |
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| 52 | .BE |
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| 53 | |
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| 54 | .SH DESCRIPTION |
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| 55 | .PP |
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| 56 | \fBTcl_UpVar\fR and \fBTcl_UpVar2\fR provide the same functionality |
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| 57 | as the \fBupvar\fR command: they make a link from a source variable |
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| 58 | to a destination variable, so that references to the destination are |
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| 59 | passed transparently through to the source. |
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| 60 | The name of the source variable may be specified either as a single |
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| 61 | string such as \fBxyx\fR or \fBa(24)\fR (by calling \fBTcl_UpVar\fR) |
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| 62 | or in two parts where the array name has been separated from the |
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| 63 | element name (by calling \fBTcl_UpVar2\fR). |
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| 64 | The destination variable name is specified in a single string; it |
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| 65 | may not be an array element. |
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| 66 | .PP |
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| 67 | Both procedures return either \fBTCL_OK\fR or \fBTCL_ERROR\fR, and they |
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| 68 | leave an error message in the interpreter's result if an error occurs. |
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| 69 | .PP |
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| 70 | As with the \fBupvar\fR command, the source variable need not exist; |
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| 71 | if it does exist, unsetting it later does not destroy the link. The |
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| 72 | destination variable may exist at the time of the call, but if so |
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| 73 | it must exist as a linked variable. |
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| 74 | |
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| 75 | .SH KEYWORDS |
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| 76 | linked variable, upvar, variable |
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