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Tcl_ListObj(3)			      Tcl Library Procedures			   Tcl_ListObj(3)

_________________________________________________________________________________________________

NAME
       Tcl_ListObjAppendList,  Tcl_ListObjAppendElement, Tcl_NewListObj, Tcl_SetListObj, Tcl_Lis-
       tObjGetElements, Tcl_ListObjLength, Tcl_ListObjIndex, Tcl_ListObjReplace - manipulate  Tcl
       objects as lists

SYNOPSIS
       #include <tcl.h>

       int
       Tcl_ListObjAppendList(interp, listPtr, elemListPtr)

       int
       Tcl_ListObjAppendElement(interp, listPtr, objPtr)

       Tcl_Obj *
       Tcl_NewListObj(objc, objv)

       Tcl_SetListObj(objPtr, objc, objv)

       int
       Tcl_ListObjGetElements(interp, listPtr, objcPtr, objvPtr)

       int
       Tcl_ListObjLength(interp, listPtr, intPtr)

       int
       Tcl_ListObjIndex(interp, listPtr, index, objPtrPtr)

       int
       Tcl_ListObjReplace(interp, listPtr, first, count, objc, objv)

ARGUMENTS
       Tcl_Interp   *interp	    (in)      If an error occurs while converting an object to be
					      a list object, an error  message	is  left  in  the
					      interpreter's result object unless interp is NULL.

       Tcl_Obj	    *listPtr	    (in/out)  Points  to  the  list object to be manipulated.  If
					      listPtr does not already point to a list object, an
					      attempt will be made to convert it to one.

       Tcl_Obj	    *elemListPtr    (in/out)  For  Tcl_ListObjAppendList,  this  points to a list
					      object containing  elements  to  be  appended  onto
					      listPtr.	 Each element of *elemListPtr will become
					      a new element of listPtr.  If *elemListPtr  is  not
					      NULL  and  does not already point to a list object,
					      an attempt will be made to convert it to one.

       Tcl_Obj	    *objPtr	    (in)      For Tcl_ListObjAppendElement,  points  to  the  Tcl
					      object  that  will  be  appended	to  listPtr.  For
					      Tcl_SetListObj, this points to the Tcl object  that
					      will  be	converted to a list object containing the
					      objc elements of the array referenced by objv.

       int	    *objcPtr	    (in)      Points  to  location  where  Tcl_ListObjGetElements
					      stores the number of element objects in listPtr.

       Tcl_Obj	    ***objvPtr	    (out)     A  location  where  Tcl_ListObjGetElements stores a
					      pointer to an array  of  pointers  to  the  element
					      objects of listPtr.

       int	    objc	    (in)      The  number of Tcl objects that Tcl_NewListObj will
					      insert into a new list object,  and  Tcl_ListObjRe-
					      place  will  insert  into listPtr.  For Tcl_SetLis-
					      tObj, the number of  Tcl	objects  to  insert  into
					      objPtr.						  |

       Tcl_Obj	    "*CONST objv[]" in								  |
					      An  array  of  pointers to objects.  Tcl_NewListObj |
					      will insert these objects into a	new  list  object |
					      and  Tcl_ListObjReplace  will  insert  them into an |
					      existing listPtr.  Each object will become a  sepa- |
					      rate list element.

       int	    *intPtr	    (out)     Points  to  location where Tcl_ListObjLength stores
					      the length of the list.

       int	    index	    (in)      Index of the list element that Tcl_ListObjIndex  is
					      to return.  The first element has index 0.

       Tcl_Obj	    **objPtrPtr     (out)     Points  to place where Tcl_ListObjIndex is to store
					      a pointer to the resulting list element object.

       int	    first	    (in)      Index of the starting list element that Tcl_ListOb-
					      jReplace	is  to replace.  The list's first element
					      has index 0.

       int	    count	    (in)      The number of elements that  Tcl_ListObjReplace  is
					      to replace.
_________________________________________________________________

DESCRIPTION
       Tcl  list objects have an internal representation that supports the efficient indexing and
       appending.  The procedures described in this man page are used to create,  modify,  index,
       and append to Tcl list objects from C code.

       Tcl_ListObjAppendList and Tcl_ListObjAppendElement both add one or more objects to the end
       of the list object referenced by listPtr.  Tcl_ListObjAppendList appends each  element  of
       the  list object referenced by elemListPtr while Tcl_ListObjAppendElement appends the sin-
       gle object referenced by objPtr.  Both procedures will convert the  object  referenced  by
       listPtr	to a list object if necessary.	If an error occurs during conversion, both proce-
       dures return TCL_ERROR and leave an error message in the interpreter's  result  object  if
       interp  is  not	NULL.  Similarly, if elemListPtr does not already refer to a list object,
       Tcl_ListObjAppendList will attempt to convert it to one and if an error occurs during con-
       version,  will  return  TCL_ERROR  and  leave an error message in the interpreter's result
       object if interp is not NULL.  Both procedures invalidate any old string representation of
       listPtr	and,  if it was converted to a list object, free any old internal representation.
       Similarly, Tcl_ListObjAppendList frees any old internal representation of  elemListPtr  if
       it converts it to a list object.  After appending each element in elemListPtr, Tcl_ListOb-
       jAppendList increments the element's reference count since listPtr now also refers to  it.
       For  the same reason, Tcl_ListObjAppendElement increments objPtr's reference count.  If no
       error occurs, the two procedures return TCL_OK after appending the objects.

       Tcl_NewListObj and Tcl_SetListObj create a new object or modify an existing object to hold
       the objc elements of the array referenced by objv where each element is a pointer to a Tcl
       object.	If objc is less than or equal to zero, they return  an	empty  object.	 The  new
       object's  string  representation is left invalid.  The two procedures increment the refer-
       ence counts of the elements in objc since the list object now refers  to  them.	 The  new
       list object returned by Tcl_NewListObj has reference count zero.

       Tcl_ListObjGetElements returns a count and a pointer to an array of the elements in a list
       object.	It returns the count by storing it in the address objcPtr.  Similarly, it returns
       the  array pointer by storing it in the address objvPtr.  The memory pointed to is managed
       by Tcl and should not be freed by the caller.  If listPtr is not already  a  list  object,
       Tcl_ListObjGetElements  will  attempt  to  convert  it to one; if the conversion fails, it
       returns TCL_ERROR and leaves an error message in the interpreter's result object if interp
       is not NULL.  Otherwise it returns TCL_OK after storing the count and array pointer.

       Tcl_ListObjLength returns the number of elements in the list object referenced by listPtr.
       It returns this count by storing an integer in the address intPtr.  If the object  is  not
       already a list object, Tcl_ListObjLength will attempt to convert it to one; if the conver-
       sion fails, it returns TCL_ERROR and leaves an error message in the  interpreter's  result
       object  if  interp  is  not  NULL.   Otherwise  it returns TCL_OK after storing the list's
       length.

       The procedure Tcl_ListObjIndex returns a pointer to the object at  element  index  in  the
       list  referenced  by  listPtr.	It  returns this object by storing a pointer to it in the
       address objPtrPtr.  If listPtr does not already refer to a list	object,  Tcl_ListObjIndex
       will  attempt  to  convert  it  to  one; if the conversion fails, it returns TCL_ERROR and
       leaves an error message in the interpreter's result object if interp is not NULL.  If  the
       index  is  out of range, that is, index is negative or greater than or equal to the number
       of elements in the list, Tcl_ListObjIndex stores a NULL in objPtrPtr and  returns  TCL_OK.
       Otherwise  it  returns  TCL_OK  after storing the element's object pointer.  The reference
       count for the list element is not incremented; the caller must do  that	if  it	needs  to
       retain a pointer to the element.

       Tcl_ListObjReplace  replaces  zero or more elements of the list referenced by listPtr with
       the objc objects in the array referenced by objv.  If listPtr does not  point  to  a  list
       object,	Tcl_ListObjReplace will attempt to convert it to one; if the conversion fails, it
       returns TCL_ERROR and leaves an error message in the interpreter's result object if interp
       is  not NULL.  Otherwise, it returns TCL_OK after replacing the objects.  If objv is NULL,
       no new elements are added.  If the argument first is zero or negative, it  refers  to  the
       first  element.	 If first is greater than or equal to the number of elements in the list,
       then no elements are deleted; the new elements are appended to the list.  count gives  the
       number of elements to replace.  If count is zero or negative then no elements are deleted;
       the new elements are simply inserted before the one designated by  first.   Tcl_ListObjRe-
       place  invalidates  listPtr's old string representation.  The reference counts of any ele-
       ments inserted from objv are incremented since the resulting  list  now	refers	to  them.
       Similarly, the reference counts for any replaced objects are decremented.

       Because Tcl_ListObjReplace combines both element insertion and deletion, it can be used to
       implement a number of list operations.  For example, the following code inserts	the  objc
       objects	referenced  by the array of object pointers objv just before the element index of
       the list referenced by listPtr:
	      result = Tcl_ListObjReplace(interp, listPtr, index, 0, objc, objv);
       Similarly, the following code appends the objc objects referenced by the array objv to the
       end of the list listPtr:
	      result = Tcl_ListObjLength(interp, listPtr, &length);
	      if (result == TCL_OK) {
		result = Tcl_ListObjReplace(interp, listPtr, length, 0, objc, objv);
	      }
       The  count list elements starting at first can be deleted by simply calling Tcl_ListObjRe-
       place with a NULL objvPtr:
	      result = Tcl_ListObjReplace(interp, listPtr, first, count, 0, NULL);

SEE ALSO
       Tcl_NewObj, Tcl_DecrRefCount, Tcl_IncrRefCount, Tcl_GetObjResult

KEYWORDS
       append, index, insert, internal representation, length,	list,  list  object,  list  type,
       object, object type, replace, string representation

Tcl					       8.0				   Tcl_ListObj(3)
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