Tcl_UpVar(3) Tcl Library Procedures Tcl_UpVar(3)
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
CONST char *sourceName (in) Name of source variable, in the frame given
by frameName. May refer to a scalar vari-
able or to an array variable with a paren-
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-
int flags (in) Either TCL_GLOBAL_ONLY or 0; if non-zero,
then destName is a global variable; other-
wise 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 destina-
tion 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
Tcl 7.4 Tcl_UpVar(3)