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

Tcl                                                    7.4                                       Tcl_UpVar(3tcl)