..
   This file is part of Logtalk <https://logtalk.org/>  
   Copyright 1998-2019 Paulo Moura <pmoura@logtalk.org>

   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:: set_logtalk_flag/2
.. _directives_set_logtalk_flag_2:

set_logtalk_flag/2
==================

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

::

   set_logtalk_flag(Flag, Value)

Sets Logtalk flag values. The scope of this directive is the entity or
the source file containing it. For global scope, use the corresponding
:ref:`predicates_set_logtalk_flag_2` built-in predicate called from an
:ref:`directives_initialization_1` directive.

Template and modes
------------------

::

   set_logtalk_flag(+atom, +nonvar)

Errors
------

| Flag is a variable:
|     ``instantiation_error``
| Value is a variable:
|     ``instantiation_error``
| Flag is not an atom:
|     ``type_error(atom, Flag)``
| Flag is neither a variable nor a valid flag:
|     ``domain_error(flag, Flag)``
| Value is not a valid value for flag Flag:
|     ``domain_error(flag_value, Flag + Value)``
| Flag is a read-only flag:
|     ``permission_error(modify, flag, Flag)``

Examples
--------

::

   % turn off the compiler unknown entity warnings
   % during the compilation of the source file:
   :- set_logtalk_flag(unknown_entities, silent).


   :- object(...).

       % generate events for messages sent from this object:
       :- set_logtalk_flag(events, allow).
       ...