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.
char *frameName (in) Identifies
the stack
frame con
taining
source vari
able. May
have any of
the forms
accepted by
the upvar
command,
such as #0
or 1.
char *sourceName (in) Name of
source vari
able, in the
frame given
by frame
Name. May
refer to a
scalar vari
able or to
an array
variable
with a
parenthe
sized index.
char *destName (in) Name of des
tination
variable,
be linked to
source vari
able so that
references
to destName
refer to the
other vari
able. Must
not cur
rently exist
except as an
upvar-ed
variable.
int flags (in) Either
TCL_GLOBAL_ONLY
or 0; if
non-zero,
then dest
Name is a
global vari
able; oth
erwise it is
a local to
the current
procedure
(or global
if no proce
dure is
active).
char *name1 (in) First part
of source
variable's
name (scalar
name, or
name of
array with
out array
index).
char *name2 (in) If source
variable is
an element
of an array,
gives the
index of the
element.
For scalar
source vari
ables, is
NULL.
_________________________________________________________________
Tcl_UpVar and Tcl_UpVar2 provide the same functionality as
the upvar command: they make a link from a source vari
able 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.
KEYWORDS
linked variable, upvar, variable
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