Tcl_ObjSetVar2(3) Tcl Library Procedures 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 containing variable.
Tcl_Obj *part1Ptr (in) Points to a Tcl object containing
the variable's name. The name
may include a series of :: names‐
pace qualifiers to specify a
variable in a particular names‐
pace. May refer to a scalar
variable or an element of an
array variable.
Tcl_Obj *part2Ptr (in) If non-NULL, points to an object
containing 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 provid‐
ing additional information for
operation. See below for valid
values.
_________________________________________________________________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 exist‐
ing 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 variable traces may modify the
variable's value. The reference 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 referenced by
newValuePtr (perhaps as a result of a variable trace), then newVal‐
uePtr'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_IncrRef‐
Count. If an error occurs in setting the variable (e.g. an array vari‐
able 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
special 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 parenthesis 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 combination of any of the follow‐
ing 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_NAMESPACE_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 modified.
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 inter‐
preted as the name of a scalar variable. When this bit is set,
part2Ptr is ignored.
Tcl_ObjGetVar2 returns the value of the specified variable. Its argu‐
ments 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 structure, it must
increment the 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.
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
Tcl 8.0 Tcl_ObjSetVar2(3)