NAME

       Tcl_UpVar, Tcl_UpVar2 - link one variable to another

SYNOPSIS

       #include <tcl.h>

       int
       Tcl_UpVar(interp, frameName, sourceName, destName, flags)

       int
       Tcl_UpVar2(interp, frameName, name1, name2, destName, flags)

ARGUMENTS

       Tcl_Interp         *interp          (in)      Interpreter containing variables;  also used
                                                     for error reporting.

       CONST char         *frameName       (in)      Identifies the stack frame containing source
                                                     variable.    May   have  any  of  the  forms
                                                     accepted by the upvar command, such as #0 or
                                                     1.

       CONST char         *sourceName      (in)      Name  of source variable, in the frame given
                                                     by  frameName.   May  refer  to   a   scalar
                                                     variable  or  to  an  array  variable with a
                                                     parenthesized index.

       CONST char         *destName        (in)      Name of destination variable, which is to be
                                                     linked to source variable so that references
                                                     to destName refer  to  the  other  variable.
                                                     Must not currently exist except as an upvar-
                                                     ed variable.

       int                flags            (in)      Either TCL_GLOBAL_ONLY or 0;   if  non-zero,
                                                     then   destName   is   a   global  variable;
                                                     otherwise it  is  a  local  to  the  current
                                                     procedure  (or  global  if  no  procedure is
                                                     active).

       CONST char         *name1           (in)      First part of source variable's name (scalar
                                                     name, or name of array without array index).

       CONST char         *name2           (in)      If  source  variable  is  an  element  of an
                                                     array, gives the index of the element.   For
                                                     scalar source variables, is NULL.
_________________________________________________________________

DESCRIPTION

       Tcl_UpVar and Tcl_UpVar2 provide the same functionality as the upvar 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  xyx  or  a(24)  (by  calling
       Tcl_UpVar)  or  in two parts where the array name has been separated from the element name
       (by calling Tcl_UpVar2).  The destination variable name is specified in a  single  string;
       it may not be an array element.

       Both  procedures return either TCL_OK or TCL_ERROR, and they leave an error message in the
       interpreter's result if an error occurs.

       As with the upvar 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.

KEYWORDS

       linked variable, upvar, variable