permission_error_3.rst

.. rst-class:: align-right

built-in method

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

permission_error/3

Description

permission_error(Operation, Permission, Culprit)

Throws an 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,Permission,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 Permission 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, Permission, 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`