Provided by: tcl8.5-doc_8.5.19-4_all 
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 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_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 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
separate 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_ListObjReplace 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
single 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
procedures 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
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 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
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 or written to by the caller. If the list is empty, 0 is
stored at objcPtr and NULL at objvPtr. 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
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 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_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 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_ListObjReplace 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