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Tcl_UpVar(3)                               Tcl Library Procedures                               Tcl_UpVar(3)



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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 report-ing. reporting.
                                            ing.

       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 paren-thesized parenthesized
                                            thesized 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 vari-able. variable.
                                            able.  Must not currently exist except as an upvar-ed  variable.

       int flags (in)                       One  of  TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY or 0;  if non-zero,
                                            then destName is a global or namespace variable;   otherwise  it
                                            is  local  to  the current procedure (or current namespace 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 trans-parently transparently
       parently 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 sep-arated separated
       arated 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 inter-preter's interpreter's
       preter'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(3)