Tcl_ObjSetVar2(3)
_________________________________________________________________
NAME
Tcl_ObjSetVar2, Tcl_ObjGetVar2 - manipulate Tcl variables
SYNOPSIS
#include <<tcl.h>>
Tcl_Obj *
Tcl_ObjSetVar2(interp, part1Ptr, part2Ptr, newValuePtr, flags)
Tcl_Obj *
Tcl_ObjGetVar2(interp, part1Ptr, part2Ptr, flags)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter contain-
ing variable.
Tcl_Obj *part1Ptr (in) Points to a Tcl
object containing
the variable's name.
The name may include
a series of ::
namespace qualifiers
to specify a vari-
able in a particular
namespace. May
refer to a scalar
variable or an ele-
ment of an array
variable.
Tcl_Obj *part2Ptr (in) If non-NULL, points
to an object con-
taining the name of
an element within an
array and part1Ptr
must refer to an
array variable.
Tcl_Obj *newValuePtr (in) Points to a Tcl
object containing
the new value for
the variable.
int flags (in) OR-ed combination of
bits providing addi-
tional information
for operation. See
below for valid val-
ues.
_________________________________________________________________
DESCRIPTION
These two procedures may be used to read and modify Tcl
variables from C code. Tcl_ObjSetVar2 will create a new
variable or modify an existing one. It sets the specified
variable to the object referenced by newValuePtr and
returns a pointer to the object which is the variable's
new value. The returned object may not be the same one
referenced by newValuePtr; this might happen because vari-
able traces may modify the variable's value. The refer-
ence count for the variable's old value is decremented and
the reference count for its new value is incremented. If
the new value for the variable is not the same one refer-
enced by newValuePtr (perhaps as a result of a variable
trace), then newValuePtr's reference count is left
unchanged. The reference count for the returned object is
not incremented to reflect the returned reference. If the
caller needs to keep a reference to the object, say in a
data structure, it must increment its reference count
using Tcl_IncrRefCount. If an error occurs in setting the
variable (e.g. an array variable is referenced without
giving an index into the array), then NULL is returned.
The variable name specified to Tcl_ObjSetVar2 consists of
two parts. part1Ptr contains the name of a scalar or
array variable. If part2Ptr is NULL, the variable must be
a scalar. If part2Ptr is not NULL, it contains the name
of an element in the array named by part2Ptr. As a spe-
cial case, if the flag TCL_PARSE_PART1 is specified,
part1Ptr may contain both an array and an element name: if
the name contains an open parenthesis and ends with a
close parenthesis, then the value between the parentheses
is treated as an element name (which can have any string
value) and the characters before the first open parenthe-
sis are treated as the name of an array variable. If the
flag TCL_PARSE_PART1 is given, part2Ptr should be NULL
since the array and element names are taken from part2Ptr.
The flags argument may be used to specify any of several
options to the procedures. It consists of an OR-ed combi-
nation of any of the following bits:
TCL_GLOBAL_ONLY
Under normal circumstances the procedures look up
variables as follows: If a procedure call is active
in interp, a variable is looked up at the current
level of procedure call. Otherwise, a variable is
looked up first in the current namespace, then in
the global namespace. However, if this bit is set
in flags then the variable is looked up only in the
global namespace even if there is a procedure call
active. If both TCL_GLOBAL_ONLY and TCL_NAMES-
PACE_ONLY are given, TCL_GLOBAL_ONLY is ignored.
TCL_NAMESPACE_ONLY
Under normal circumstances the procedures look up
variables as follows: If a procedure call is active
in interp, a variable is looked up at the current
level of procedure call. Otherwise, a variable is
looked up first in the current namespace, then in
the global namespace. However, if this bit is set
in flags then the variable is looked up only in the
current namespace even if there is a procedure call
active.
TCL_LEAVE_ERR_MSG
If an error is returned and this bit is set in
flags, then an error message will be left in the
interpreter's result, where it can be retrieved
with Tcl_GetObjResult or Tcl_GetStringResult. If
this flag bit isn't set then no error message is
left and the interpreter's result will not be modi-
fied.
TCL_APPEND_VALUE
If this bit is set then newValuePtr is appended to
the current value, instead of replacing it. If the
variable is currently undefined, then this bit is
ignored.
TCL_LIST_ELEMENT
If this bit is set, then newValuePtr is converted
to a valid Tcl list element before setting (or
appending to) the variable. A separator space is
appended before the new list element unless the
list element is going to be the first element in a
list or sublist (i.e. the variable's current value
is empty, or contains the single character ``{'',
or ends in `` }'').
TCL_PARSE_PART1
If this bit is set, then Tcl_ObjGetVar2 and
Tcl_ObjSetVar2 will parse part1Ptr to obtain both
an array name and an element name. If the name in
part1Ptr contains an open parenthesis and ends with
a close parenthesis, the name is treated as the
name of an element of an array; otherwise, the name
in part1Ptr is interpreted as the name of a scalar
variable. When this bit is set, part2Ptr is
ignored.
Tcl_ObjGetVar2 returns the value of the specified vari-
able. Its arguments are treated the same way as those for
Tcl_ObjSetVar2. It returns a pointer to the object which
is the variable's value. The reference count for the
returned object is not incremented. If the caller needs
to keep a reference to the object, say in a data struc-
ture, it must increment the reference count using
Tcl_IncrRefCount. If an error occurs in setting the vari-
able (e.g. an array variable is referenced without giving
an index into the array), then NULL is returned.
SEE ALSO
Tcl_GetObjResult, Tcl_GetStringResult, Tcl_GetVar,
Tcl_GetVar2, Tcl_SetVar, Tcl_SetVar2, Tcl_TraceVar,
Tcl_UnsetVar, Tcl_UnsetVar2
KEYWORDS
array, interpreter, object, scalar, set, unset, variable