Tcl_UpVar(3) Tcl Library Procedures Tcl_UpVar(3) 







Tcl_UpVar, Tcl_UpVar2 - link one variable to another








#include <tcl.h>

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

int
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
      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.
    
    

    

  










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.










linked variable, upvar, variable







  

    7.4
    Tcl