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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 including both  variable  name  and  index.   May
                                             include :: namespace qualifiers to specify a variable in a par-ticular particular
                                             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. variable.
                                             able.

       int flags (in)                        OR-ed combination of bits providing additional information. See
                                             below for valid values.

       const char *varName (in)              Name of variable.  May include :: namespace qualifiers to spec-ify specify
                                             ify a variable in a  particular  namespace.   May  refer  to  a
                                             scalar variable or an element of an array.

       const char *newValue (in)             New  value for variable, 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 particular namespace.  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 ele-ment element
                                             ment within an array and part1Ptr must refer to an array  vari-able. variable.
                                             able.
____________________________________________________________________________________________________________


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  modifications  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  arguments  to  the  procedures
       described  above.  Under normal circumstances, 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 usually 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 variable, 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
       message is left in interp's result if the TCL_LEAVE_ERR_MSG 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 variable.  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  con-tains contains
              tains 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 combination 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, the variable is looked up at the current level of procedure call.  Other-wise, Otherwise,
              wise, 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 names-pace namespace
              pace 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 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_GetStringRe-sult. Tcl_GetStringResult.
              sult.   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* procedures.

       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 single character "{", or ends in " }").  When append-ing, appending,
              ing, 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  circum-stances, circumstances,
       stances,  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 variable), then NULL is returned.

       Tcl_UnsetVar  and  Tcl_UnsetVar2 may be used to remove a variable, 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 element is removed but the array
       remains.  If an array name is specified without an index, then the entire array is removed.


SEE ALSO
       Tcl_GetObjResult, Tcl_GetStringResult, Tcl_TraceVar


KEYWORDS
       array, get variable, interpreter, object, scalar, set, unset, variable



Tcl                                                  8.1                                       Tcl_SetVar(3)