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 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  vari-
						     able.

       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.
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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 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 ele-
       ment.

       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 desti-
       nation 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)