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