Tcl_UpVar, Tcl_UpVar2 - link one variable to another
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
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 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.
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