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.. _lua_object_manager_api:
Object Manager
==============
The ObjectManager (binding for :c:struct:`WpObjectManager`) provides a way to
collect a set of objects and be notified when objects that fulfill a certain
set of criteria are created or destroyed.
To start an object manager, you first need to declare interest in a certain
kind of object specifying a set of :ref:`Interests <lua_object_interest_api>`
in the constructor and then you need to activate it by calling
:func:`ObjectManager.activate`
Upon activating an ObjectManager, any pre-existing objects that match the
specified interests will immediately become available to get through
:func:`ObjectManager.iterate` and the :c:struct:`WpObjectManager` "object-added"
signal will be emitted for all of them.
Constructors
~~~~~~~~~~~~
.. function:: ObjectManager(interest_list)
Constructs a new object manager.
Combines :c:func:`wp_object_manager_new` and
:c:func:`wp_object_manager_add_interest_full`
The argument needs to be a table that contains one or more
:ref:`Interest <lua_object_interest_api>` objects. The object manager
will then contain all objects that match any one of the supplied interests.
Example:
.. code-block:: lua
streams_om = ObjectManager {
-- match stream nodes
Interest {
type = "node",
Constraint { "media.class", "matches", "Stream/*", type = "pw-global" },
},
-- and device nodes that are not associated with any routes
Interest {
type = "node",
Constraint { "media.class", "matches", "Audio/*", type = "pw-global" },
Constraint { "device.routes", "equals", "0", type = "pw" },
},
Interest {
type = "node",
Constraint { "media.class", "matches", "Audio/*", type = "pw-global" },
Constraint { "device.routes", "is-absent", type = "pw" },
},
}
The above example will create an ObjectManager that matches all nodes with
a "media.class" global property that starts with the string "Stream/"
and additionally all those whose "media.class" starts with "Audio/" and
they have either a "device.routes" property that equals zero or they
don't have a "device.routes" property at all.
:param table interest_list: a list of :ref:`interests <lua_object_interest_api>`
to objects
:returns: a new object manager
:rtype: ObjectManager (:c:struct:`WpObjectManager`)
Methods
~~~~~~~
.. function:: ObjectManager.activate(self)
Activates the object manager.
Binds :c:func:`wp_core_install_object_manager`.
:param self: the object manager
.. function:: ObjectManager.get_n_objects(self)
Binds :c:func:`wp_object_manager_get_n_objects`
:param self: the object manager
:returns: the number of objects managed by the object manager
:rtype: integer
.. function:: ObjectManager.iterate(self, interest)
Binds :c:func:`wp_object_manager_new_filtered_iterator_full`
:param self: the object manager
:param interest: an interest to filter objects
:type interest: :ref:`Interest <lua_object_interest_api>` or nil or none
:returns: all the managed objects that match the interest
:rtype: Iterator; the iteration items are of type :ref:`GObject <lua_gobject>`
.. function:: ObjectManager.lookup(self, interest)
Binds :c:func:`wp_object_manager_lookup`
:param self: the object manager
:param interest: the interest to use for the lookup
:type interest: :ref:`Interest <lua_object_interest_api>` or nil or none
:returns: the first managed object that matches the interest
:rtype: :ref:`GObject <lua_gobject>`
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