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Tcl_SetVar(3)		    Tcl Library Procedures		 Tcl_SetVar(3)

______________________________________________________________________________

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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