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   SPDX-FileCopyrightText: 1998-2025 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.
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.. rst-class:: align-right

**built-in method**

.. index:: pair: permission_error/3; Built-in method
.. _methods_permission_error_3:

``permission_error/3``
======================

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

::

   permission_error(Operation, PermissionType, Culprit)

Throws a permission error. Used when an operation is not allowed. For example,
sending a message for a predicate that is not within the scope of the sender.
This built-in method is declared private and thus cannot be used as a message
to an object. Calling this predicate is equivalent to the following sequence
of goals:

::

   ...,
   context(Context),
   throw(error(permission_error(Operation,PermissionType,Culprit), Context)).

This allows the user to generate errors in the same format used by the
runtime.

Possible values for ``Operation`` include:

- ``access``
- ``create``
- ``declare``
- ``define``
- ``modify``
- ``open``
- ``input``
- ``output``
- ``reposition``
- ``repeat``

Possible values for ``PermissionType`` include:

- ``predicate_declaration``
- ``protected_predicate``
- ``private_predicate``
- ``static_predicate``
- ``dynamic_predicate``
- ``predicate``
- ``non_terminal``
- ``database``
- ``object``
- ``static_object``
- ``static_protocol``
- ``static_category``
- ``entity_relation``
- ``operator``
- ``flag``
- ``engine``
- ``binary_stream``
- ``text_stream``
- ``source_sink``
- ``stream``
- ``past_end_of_stream``

The value of ``Culprit`` is the argument or one of its sub-terms that caused
the error.

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

::

   permission_error(@nonvar, @nonvar, @nonvar) - error

Errors
------

| When called:
|     ``permission_error(Operation, PermissionType, Culprit)``

Examples
--------

::

   ...,
   \+ writable(File),
   permission_error(modify, file, File).

.. seealso::

   :ref:`methods_catch_3`,
   :ref:`methods_throw_1`,
   :ref:`methods_context_1`,
   :ref:`methods_instantiation_error_0`,
   :ref:`methods_uninstantiation_error_1`,
   :ref:`methods_type_error_2`,
   :ref:`methods_domain_error_2`,
   :ref:`methods_consistency_error_3`,
   :ref:`methods_existence_error_2`,
   :ref:`methods_representation_error_1`,
   :ref:`methods_evaluation_error_1`,
   :ref:`methods_resource_error_1`,
   :ref:`methods_syntax_error_1`,
   :ref:`methods_system_error_0`
