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Tcl_SetVar2Ex(3tcl)




______________________________________________________________________________


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 namespace.

       CONST char   *name2         (in)      If non-NULL, gives name  of  ele-
                                             ment  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 variable.

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

       CONST char   *varName       (in)      Name of variable.  May include ::
                                             namespace qualifiers to specify a
                                             variable in a  particular  names-
                                             pace.   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 :: 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.
_________________________________________________________________


DESCRIPTION

       These procedures are used to create, modify, read, and delete Tcl vari-
       ables 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  vari- |
       able 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_Set- |
       Var2  take the new value as a string and return a string; they are usu- |
       ally less efficient than Tcl_ObjSetVar2.  Note that  the  return  value |
       may be different than the newValuePtr or newValue argument, due to mod-
       ifications 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 doesn't 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  argu-
       ments to the procedures above.  If the variable is successfully removed
       then TCL_OK is returned.  If the variable cannot be removed because  it
       doesn't  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 vari-
              able name is given as a single string, varName.  If varName con-
              tains 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 doesn't have parentheses as  described  above,
              then  the entire string is treated as the name of a scalar vari-
              able.

       [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 paren- |
              thesis (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.  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 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 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 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 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  argu-
       ments  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 doesn't 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 vari-
       able is successfully removed then TCL_OK is returned.  If the  variable
       cannot  be removed because it doesn't 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)

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