Tcl_UpVar(3TCL) Tcl Library Procedures Tcl_UpVar(3TCL)
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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.
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 vari-
able.
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.
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DESCRIPTION
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 ele-
ment.
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 desti-
nation variable may exist at the time of the call, but if so it must exist as a linked variable.
KEYWORDS
linked variable, upvar, variable
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Availability | SUNWTcl |
+--------------------+-----------------+
|Interface Stability | Uncommitted |
+--------------------+-----------------+
NOTES
Source for Tcl is available on http://opensolaris.org.
Tcl 7.4 Tcl_UpVar(3TCL)