'\" '\" Copyright (c) 1994 The Regents of the University of California. '\" Copyright (c) 1994-1996 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: UpVar.3,v 1.2 2001/09/14 01:42:17 zlaski Exp $ '\" .so man.macros .TH Tcl_UpVar 3 7.4 Tcl "Tcl Library Procedures" .BS .SH NAME Tcl_UpVar, Tcl_UpVar2 \- link one variable to another .SH SYNOPSIS .nf \fB#include <tcl.h>\fR .sp int \fBTcl_UpVar(\fIinterp, frameName, sourceName, destName, flags\fB)\fR .sp int \fBTcl_UpVar2(\fIinterp, frameName, name1, name2, destName, flags\fB)\fR .SH ARGUMENTS .AS Tcl_VarTraceProc prevClientData .AP Tcl_Interp *interp in Interpreter containing variables; also used for error reporting. .AP char *frameName in Identifies the stack frame containing source variable. May have any of the forms accepted by the \fBupvar\fR command, such as \fB#0\fR or \fB1\fR. .AP char *sourceName in Name of source variable, in the frame given by \fIframeName\fR. May refer to a scalar variable or to an array variable with a parenthesized index. .AP char *destName in Name of destination variable, which is to be linked to source variable so that references to \fIdestName\fR refer to the other variable. Must not currently exist except as an upvar-ed variable. .AP int flags in Either TCL_GLOBAL_ONLY or 0; if non-zero, then \fIdestName\fR is a global variable; otherwise it is a local to the current procedure (or global if no procedure is active). .AP char *name1 in First part of source variable's name (scalar name, or name of array without array index). .AP char *name2 in If source variable is an element of an array, gives the index of the element. For scalar source variables, is NULL. .BE .SH DESCRIPTION .PP \fBTcl_UpVar\fR and \fBTcl_UpVar2\fR provide the same functionality as the \fBupvar\fR command: they make a link from a source variable to a destination variable, so that references to the destination are passed transparently through to the source. The name of the source variable may be specified either as a single string such as \fBxyx\fR or \fBa(24)\fR (by calling \fBTcl_UpVar\fR) or in two parts where the array name has been separated from the element name (by calling \fBTcl_UpVar2\fR). The destination variable name is specified in a single string; it may not be an array element. .PP Both procedures return either TCL_OK or TCL_ERROR, and they leave an error message in \fIinterp->result\fR if an error occurs. .PP As with the \fBupvar\fR command, the source variable need not exist; if it does exist, unsetting it later does not destroy the link. The destination variable may exist at the time of the call, but if so it must exist as a linked variable. .SH KEYWORDS linked variable, upvar, variable