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

   Unless required by applicable law or agreed to in writing, software
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.. index:: imports_category/2-3
.. _predicates_imports_category_2_3:

imports_category/2-3
====================

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

::

   imports_category(Object, Category)

   imports_category(Object, Category, Scope)

Enumerates, by backtracking, importation relations between objects and
categories. The relation scope is represented by the atoms ``public``,
``protected``, and ``private``.

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

::

   imports_category(?object_identifier, ?category_identifier) - zero_or_more
   imports_category(?object_identifier, ?category_identifier, ?scope) - zero_or_more

Errors
------

| Object is neither a variable nor a valid object identifier:
|     ``type_error(object_identifier, Object)``
| Category is neither a variable nor a valid category identifier:
|     ``type_error(category_identifier, Category)``
| Scope is neither a variable nor an atom:
|     ``type_error(atom, Scope)``
| Scope is an atom but an invalid entity scope:
|     ``domain_error(scope, Scope)``

Examples
--------

::

   % check that the xref_diagram object imports the diagram category:
   | ?- imports_category(xref_diagram, diagram).

   % enumerate the objects that privately import the diagram category:
   | ?- imports_category(Object, diagram, private).

.. seealso::

   :ref:`predicates_current_category_1`,
   :ref:`predicates_complements_object_2`
