NAME

       Tcl_ListObjAppendList,           Tcl_ListObjAppendElement,
       Tcl_NewListObj,  Tcl_SetListObj,   Tcl_ListObjGetElements,
       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 manip­
                                              ulated.  If listPtr
                                              does   not  already
                                              point  to  a   list
                                              object,  an attempt
                                              will  be  made   to
                                              convert  it to one.
                                              pendList,      this
                                              points  to  a  list
                                              object   containing
                                              elements   to    be
                                              appended       onto
                                              listPtr.  Each ele­
                                              ment    of   *elem­
                                              ListPtr will become
                                              a  new  element  of
                                              listPtr.  If *elem­
                                              ListPtr 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_ListObjAp­
                                              pendElement, 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_ListOb­
                                              jGetElements stores
                                              the number of  ele­
                                              ment   objects   in
                                              listPtr.

       Tcl_Obj      ***objvPtr      (out)     A  location   where
                                              Tcl_ListObjGetEle­
                                              ments   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
                                              Tcl_ListObjReplace
                                              will  insert   into
                                              listPtr.        For
                                              Tcl_SetListObj, the
                                              number    of    Tcl
                                              objects  to  insert
                                              into objPtr.        |

       Tcl_Obj      "*CONST objv[]" in                                   ||
                                              An array of  point­ |
                                              ers   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   separate   list |
                                              element.

       int          *intPtr         (out)     Points to  location
                                              where   Tcl_ListOb­
                                              jLength 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_ListOb­
                                              jIndex  is to store
                                              a  pointer  to  the
                                              resulting list ele­
                                              ment object.

       int          first           (in)      Index of the start­
                                              ing   list  element
                                              that Tcl_ListObjRe­
                                              place     is     to
                                              replace.        The
                                              list's  first  ele­
                                              ment has index 0.

       int          count           (in)      The number of  ele­
                                              ments that Tcl_Lis­

_________________________________________________________________



DESCRIPTION

       Tcl list objects have an internal representation that sup­
       ports the efficient indexing and  appending.   The  proce­
       dures  described in this man page are used to create, mod­
       ify, 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 ref­
       erenced by listPtr.   Tcl_ListObjAppendList  appends  each
       element of the list object referenced by elemListPtr while
       Tcl_ListObjAppendElement appends the single object  refer­
       enced  by objPtr.  Both procedures will convert the object
       referenced by listPtr to a list object if  necessary.   If
       an  error occurs during conversion, both procedures return
       TCL_ERROR and leave an error message in the  interpreter's
       result  object if interp is not NULL.  Similarly, if elem­
       ListPtr does not already refer to a list object,  Tcl_Lis­
       tObjAppendList will attempt to convert it to one and if an
       error occurs during conversion, 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_ListObjAppendList increments the  element's  reference
       count  since  listPtr now also refers to it.  For the same
       reason, Tcl_ListObjAppendElement increments objPtr's  ref­
       erence  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 rep­
       resentation is left invalid.  The two procedures increment
       the reference 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
       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  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 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 num­
       ber  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  incre­
       mented;  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  ele­
       ments  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 desig­
       nated  by first.  Tcl_ListObjReplace invalidates listPtr's
       old string representation.  The reference  counts  of  any
       elements  inserted  from  objv  are  incremented since the
       resulting list now refers to them.  Similarly, the  refer­
       ence 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
       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_ListObjReplace with a NULL objvPtr:
              result = Tcl_ListObjReplace(interp, listPtr, first, count, 0, NULL);



SEE ALSO

       Tcl_NewObj, Tcl_DecrRefCount, Tcl_IncrRefCount, Tcl_GetOb­
       jResult



KEYWORDS

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