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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 in-
					     clude  :: namespace qualifiers to
					     specify a variable	in a  particu-
					     lar 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 value  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 name-
					     space.  May  refer	 to  a	scalar
					     variable  or an element of	an ar-
					     ray.

       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 value containing
					     the variable's  name.   The  name
					     may  include a series of :: name-
					     space  qualifiers	to  specify  a
					     variable  in  a  particular name-
					     space.  May  refer	 to  a	scalar
					     variable  or an element of	an ar-
					     ray variable.

       Tcl_Obj *part2Ptr (in)		     If	non-NULL, points  to  a	 value
					     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 in-
       terp'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  ar-
       ray  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
       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 ar-
       ray element is specified, the given element is removed  but  the	 array
       remains.	  If an	array name is specified	without	an index, then the en-
       tire 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 does not 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 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	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 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	 vari-
       able  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, scalar, set, unset, value, variable

Tcl				      8.1			 Tcl_SetVar(3)

NAME | SYNOPSIS | ARGUMENTS | DESCRIPTION | SEE ALSO | KEYWORDS

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