Tcl_SetVar2Ex(3tcl)
Tcl_SetVar(3) Tcl Library Procedures Tcl_SetVar(3)
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NAME
Tcl_SetVar2Ex, Tcl_SetVar, Tcl_SetVar2, Tcl_ObjSetVar2,
Tcl_GetVar2Ex, Tcl_GetVar, Tcl_GetVar2, Tcl_ObjGetVar2,
Tcl_UnsetVar, Tcl_UnsetVar2 - manipulate Tcl variables
SYNOPSIS
#include <tcl.h>
Tcl_Obj *
Tcl_SetVar2Ex(interp, name1, name2, newValuePtr, flags)
const char *
Tcl_SetVar(interp, varName, newValue, flags)
const char *
Tcl_SetVar2(interp, name1, name2, newValue, flags)
Tcl_Obj *
Tcl_ObjSetVar2(interp, part1Ptr, part2Ptr, newValuePtr, flags)
Tcl_Obj *
Tcl_GetVar2Ex(interp, name1, name2, flags)
const char *
Tcl_GetVar(interp, varName, flags)
const char *
Tcl_GetVar2(interp, name1, name2, flags)
Tcl_Obj *
Tcl_ObjGetVar2(interp, part1Ptr, part2Ptr, flags)
int
Tcl_UnsetVar(interp, varName, flags)
int
Tcl_UnsetVar2(interp, name1, name2, flags)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter containing
variable.
const char *name1 (in) Contains the name of
an array variable (if
name2 is non-NULL) or
(if name2 is NULL)
either the name of a
scalar variable or a
complete name includ-
ing both variable name
Tcl Last change: 8.1 1
Tcl_SetVar(3) Tcl Library Procedures Tcl_SetVar(3)
and index. May
include :: namespace
qualifiers to specify
a variable in a par-
ticular namespace.
const char *name2 (in) If non-NULL, gives
name of element within
array; in this case
name1 must refer to an
array variable.
Tcl_Obj *newValuePtr (in) Points to a Tcl object
containing the new
value for the vari-
able.
int flags (in) OR-ed combination of
bits providing addi-
tional information.
See below for valid
values.
const char *varName (in) Name of variable. May
include :: namespace
qualifiers to specify
a variable in a par-
ticular namespace.
May refer to a scalar
variable or an element
of an array.
const char *newValue (in) New value for vari-
able, specified as a
null-terminated
string. A copy of
this value is stored
in the 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 variable in a par-
ticular namespace.
May refer to a scalar
variable or an element
of an array variable.
Tcl_Obj *part2Ptr (in) If non-NULL, points to
Tcl Last change: 8.1 2
Tcl_SetVar(3) Tcl Library Procedures Tcl_SetVar(3)
an object containing
the name of an element
within an array and
part1Ptr must refer to
an array variable.
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DESCRIPTION
These procedures are used to create, modify, read, and
delete Tcl variables from C code.
Tcl_SetVar2Ex, Tcl_SetVar, Tcl_SetVar2, and Tcl_ObjSetVar2
will create a new variable or modify an existing one. These
procedures set the given variable to the value given by
newValuePtr or newValue and return a pointer to the
variable's new value, which is stored in Tcl's variable
structure. Tcl_SetVar2Ex and Tcl_ObjSetVar2 take the new
value as a Tcl_Obj and return a pointer to a Tcl_Obj.
Tcl_SetVar and Tcl_SetVar2 take the new value as a string
and return a string; they are usually less efficient than
Tcl_ObjSetVar2. Note that the return value may be different
than the newValuePtr or newValue argument, due to modifica-
tions made by write traces. If an error occurs in setting
the variable (e.g. an array variable is referenced without
giving an index into the array) NULL is returned and an
error message is left in interp's result if the
TCL_LEAVE_ERR_MSG flag bit is set.
Tcl_GetVar2Ex, Tcl_GetVar, Tcl_GetVar2, and Tcl_ObjGetVar2
return the current value of a variable. The arguments to
these procedures are treated in the same way as the argu-
ments to the procedures described above. Under normal cir-
cumstances, the return value is a pointer to the variable's
value. For Tcl_GetVar2Ex and Tcl_ObjGetVar2 the value is
returned as a pointer to a Tcl_Obj. For Tcl_GetVar and
Tcl_GetVar2 the value is returned as a string; this is usu-
ally less efficient, so Tcl_GetVar2Ex or Tcl_ObjGetVar2 are
preferred. If an error occurs while reading the variable
(e.g. the variable does not exist or an array element is
specified for a scalar variable), then NULL is returned and
an error message is left in interp's result if the
TCL_LEAVE_ERR_MSG flag bit is set.
Tcl_UnsetVar and Tcl_UnsetVar2 may be used to remove a vari-
able, so that future attempts to read the variable will
return an error. The arguments to these procedures are
treated in the same way as the arguments to the procedures
above. If the variable is successfully removed then TCL_OK
is returned. If the variable cannot be removed because it
does not exist then TCL_ERROR is returned and an error mes-
sage is left in interp's result if the TCL_LEAVE_ERR_MSG
Tcl Last change: 8.1 3
Tcl_SetVar(3) Tcl Library Procedures Tcl_SetVar(3)
flag bit is set. If an array element is specified, the
given element is removed but the array remains. If an array
name is specified without an index, then the entire array is
removed.
The name of a variable may be specified to these procedures
in four ways:
[1] If Tcl_SetVar, Tcl_GetVar, or Tcl_UnsetVar is invoked,
the variable name is given as a single string, varName.
If varName contains an open parenthesis and ends with a
close parenthesis, then the value between the
parentheses is treated as an index (which can have any
string value) and the characters before the first open
parenthesis are treated as the name of an array vari-
able. If varName does not have parentheses as
described above, then the entire string is treated as
the name of a scalar variable.
[2] If the name1 and name2 arguments are provided and name2
is non-NULL, then an array element is specified and the
array name and index have already been separated by the
caller: name1 contains the name and name2 contains the
index. An error is generated if name1 contains an
open parenthesis and ends with a close parenthesis
(array element) and name2 is non-NULL.
[3] If name2 is NULL, name1 is treated just like varName in
case [1] above (it can be either a scalar or an array
element variable name).
The flags argument may be used to specify any of several
options to the procedures. It consists of an OR-ed combina-
tion of the following bits.
TCL_GLOBAL_ONLY
Under normal circumstances the procedures look up vari-
ables as follows. If a procedure call is active in
interp, the variable is looked up at the current level
of procedure call. Otherwise, the 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
If this bit is set in flags then the variable is looked
up only in the current namespace; if a procedure is
active its variables are ignored, and the global
namespace is also ignored unless it is the current
Tcl Last change: 8.1 4
Tcl_SetVar(3) Tcl Library Procedures Tcl_SetVar(3)
namespace.
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 is not 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 or newValue is
appended to the current value instead of replacing it.
If the variable is currently undefined, then the bit is
ignored. This bit is only used by the Tcl_Set* pro-
cedures.
TCL_LIST_ELEMENT
If this bit is set, then newValue 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 sin-
gle character "{", or ends in " }"). When appending,
the original value of the variable must also be a valid
list, so that the operation is the appending of a new
list element onto a list.
Tcl_GetVar and Tcl_GetVar2 return the current value of a
variable. The arguments to these procedures are treated in
the same way as the arguments to Tcl_SetVar and Tcl_SetVar2.
Under normal circumstances, the return value is a pointer to
the variable's value (which is stored in Tcl's variable
structure and will not change before the next call to
Tcl_SetVar or Tcl_SetVar2). Tcl_GetVar and Tcl_GetVar2 use
the flag bits TCL_GLOBAL_ONLY and TCL_LEAVE_ERR_MSG, both of
which have the same meaning as for Tcl_SetVar. If an error
occurs in reading the variable (e.g. the variable does not
exist or an array element is specified for a scalar vari-
able), then NULL is returned.
Tcl_UnsetVar and Tcl_UnsetVar2 may be used to remove a vari-
able, so that future calls to Tcl_GetVar or Tcl_GetVar2 for
the variable will return an error. The arguments to these
procedures are treated in the same way as the arguments to
Tcl_GetVar and Tcl_GetVar2. If the variable is successfully
removed then TCL_OK is returned. If the variable cannot be
removed because it does not exist then TCL_ERROR is
returned. If an array element is specified, the given ele-
ment is removed but the array remains. If an array name is
specified without an index, then the entire array is
Tcl Last change: 8.1 5
Tcl_SetVar(3) Tcl Library Procedures Tcl_SetVar(3)
removed.
SEE ALSO
Tcl_GetObjResult, Tcl_GetStringResult, Tcl_TraceVar
KEYWORDS
array, get variable, interpreter, object, scalar, set,
unset, variable
Tcl Last change: 8.1 6
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