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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
                                                     reporting.

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

       CONST char         *sourceName      (in)      Name of source variable, in the frame given  by  frame-Name. frameName.
                                                     Name.   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 dest-Name destName
                                                     Name 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.
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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)