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Tcl_UpVar(3)                Tcl Library Procedures                Tcl_UpVar(3)


       Tcl_UpVar, Tcl_UpVar2 - link one variable to another

       #include <tcl.h>

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

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

       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  cur-
                                            rently exist except as an upvar-ed variable.

       int flags (in)                       One  of TCL_GLOBAL_ONLY, TCL_NAMESPACE_ONLY or 0;  if non-zero, then dest-
                                            Name is a global or namespace variable;  otherwise it is local to the cur-
                                            rent 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 with-
                                            out array index).

       const char *name2 (in)               If source variable is an element of an array, gives the index of the  ele-
                                            ment.  For scalar source variables, is NULL.

       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  call-
       ing  Tcl_UpVar2).   The destination variable name is specified in a single string;  it may not be an array ele-

       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.

       linked variable, upvar, variable

Tcl                                   7.4                         Tcl_UpVar(3)