Tcl_ListObjAppendList(3tcl)
Tcl_ListObj(3) Tcl Library Procedures Tcl_ListObj(3)
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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 mani-
pulated. If
listPtr does not
already point to a
list object, an
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Tcl_ListObj(3) Tcl Library Procedures Tcl_ListObj(3)
attempt will be
made to convert it
to one.
Tcl_Obj *elemListPtr (in/out) For
Tcl_ListObjAppendList,
this points to a
list object con-
taining elements
to be appended
onto listPtr.
Each element of
*elemListPtr will
become a new ele-
ment 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 refer-
enced 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
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Tcl_ListObj(3) Tcl Library Procedures Tcl_ListObj(3)
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.
Tcl Last change: 8.0 3
Tcl_ListObj(3) Tcl Library Procedures Tcl_ListObj(3)
int first (in) Index of the
starting list ele-
ment that
Tcl_ListObjReplace
is to replace.
The list's first
element has index
0.
int count (in) The number of ele-
ments that
Tcl_ListObjReplace
is to replace.
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DESCRIPTION
Tcl list objects have an internal representation that sup-
ports 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 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_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 con-
verted to a list object, free any old internal representa-
tion. Similarly, Tcl_ListObjAppendList frees any old inter-
nal 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 refer-
ence 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
Tcl Last change: 8.0 4
Tcl_ListObj(3) Tcl Library Procedures Tcl_ListObj(3)
return an empty object. The new object's string representa-
tion 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. Other-
wise 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
Tcl Last change: 8.0 5
Tcl_ListObj(3) Tcl Library Procedures Tcl_ListObj(3)
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
Tcl Last change: 8.0 6
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