..
   This file is part of Logtalk <https://logtalk.org/>  
   Copyright 1998-2021 Paulo Moura <pmoura@logtalk.org>
   SPDX-License-Identifier: Apache-2.0

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.


.. index:: pair: findall/4; Built-in method
.. _methods_findall_4:

``findall/4``
=============

Description
-----------

::

   findall(Template, Goal, List, Tail)

Variant of the :ref:`methods_findall_3` method that allows passing the
tail of the results list. It succeeds returning the tail argument when
the goal has no solutions.

This built-in meta-predicate is declared as a private method and thus
cannot be used as a message to an object.

Modes and number of proofs
--------------------------

::

   findall(?term, +callable, ?list, ?term) - zero_or_one

Errors
------

| ``Goal`` is a variable:
|     ``instantiation_error``
| ``Goal`` is neither a variable nor a callable term:
|     ``type_error(callable, Goal)``
| ``Goal`` is a call to a non-existing predicate:
|     ``existence_error(procedure, Predicate)``

Examples
--------

| To find all solutions in the context of the object or category containing the call:
|     ``findall(Template, Goal, List, Tail)``
| To find all solutions of sending a message to :term:`self`:
|     ``findall(Template, ::Message, List, Tail)``
| To find all solutions of sending a message to an explicit object:
|     ``findall(Template, Object::Message, List, Tail)``

.. seealso::

   :ref:`methods_bagof_3`,
   :ref:`methods_findall_3`,
   :ref:`methods_forall_2`,
   :ref:`methods_setof_3`
