.. index:: pair: class; EE::UI::UIProperty::WeakHandle
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle:

class EE::UI::UIProperty::WeakHandle
====================================

.. toctree::
	:hidden:

Overview
~~~~~~~~

Lifetime-safe, non-owning access used by containers such as :ref:`UIBindingGroup <doxid-class_e_e_1_1_u_i_1_1_u_i_binding_group>`. :ref:`More...<details-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle>`


.. ref-code-block:: cpp
	:class: doxyrest-overview-code-block

	#include <uiproperty.hpp>
	
	class WeakHandle {
	public:
		// methods
	
		std::optional<T> :ref:`get<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a6773c929642c5a180d0a8613435626e4>`() const;
		bool :ref:`set<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1ad5430dfed908af7dcfd45fade14e98b5>`(const T& value) const;
		:ref:`Connection<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1a34371cd28009360162b4b58dec06d129>` :ref:`observe<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1adcba8e59c867a6c61cabb249cca517fe>`(:ref:`Callback<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1af0b2199933de7f6ad187c5240e065ad9>` callback) const;
		:ref:`ObservableValue<doxid-class_e_e_1_1_observable_value>`<bool>:::ref:`Connection<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1a34371cd28009360162b4b58dec06d129>` :ref:`observeLifetime<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a2914c8d1a46d79de130c4b7a53b948eb>`(:ref:`ObservableValue<doxid-class_e_e_1_1_observable_value>`<bool>:::ref:`Callback<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1af0b2199933de7f6ad187c5240e065ad9>` callback) const;
		:ref:`ValidationConnection<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1a9625ca3d0a1d23aa97c50a389db64924>` :ref:`observeValidation<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1aaee4f0ab7c50d99c4e8bc219ef6ad140>`(:ref:`UIValueValidationState::Callback<doxid-class_e_e_1_1_u_i_1_1_u_i_value_validation_state_1a7f90f7554ee6794307c5554625bc24b0>` callback) const;
		:ref:`UIValueValidationResult<doxid-struct_e_e_1_1_u_i_1_1_u_i_value_validation_result>` :ref:`validation<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a3426744432ff5d2d0ed6f474c4395be3>`() const;
		:ref:`UIWidget<doxid-class_e_e_1_1_u_i_1_1_u_i_widget>`* :ref:`validationEmitter<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a900f7885e7e12a6ad429319e4ec8189c>`() const;
		std::vector<:ref:`UIWidget<doxid-class_e_e_1_1_u_i_1_1_u_i_widget>`*> :ref:`widgets<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1abb19baeada56beb79b2f0c3fe883cc5d>`() const;
	
		template <typename Container>
		void :ref:`appendWidgets<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1ace3e7add749eadea1ff8dfd3d8ab25f7>`(:ref:`Container<doxid-class_e_e_1_1_system_1_1_container>`& destination) const;
	
		template <typename WidgetCallback>
		void :ref:`forEachWidget<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a924636c013288d500876acbf2e8790ea>`(WidgetCallback&& callback) const;
	
		:ref:`UIWidget<doxid-class_e_e_1_1_u_i_1_1_u_i_widget>`* :ref:`firstEnabledWidget<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a1c11e990552248863a74662321772bfd>`() const;
		:target:`operator bool<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a7c92c228dccf94c2b7960a0d62542992>`() const;
	};
.. _details-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle:

Detailed Documentation
~~~~~~~~~~~~~~~~~~~~~~

Lifetime-safe, non-owning access used by containers such as :ref:`UIBindingGroup <doxid-class_e_e_1_1_u_i_1_1_u_i_binding_group>`.

Every operation becomes a harmless no-op or empty result after the :ref:`UIProperty <doxid-class_e_e_1_1_u_i_1_1_u_i_property>` is destroyed. Like :ref:`UIProperty <doxid-class_e_e_1_1_u_i_1_1_u_i_property>` itself, this handle is restricted to the widgets' owning :ref:`UI <doxid-namespace_e_e_1_1_u_i>` thread.

Methods
-------

.. index:: pair: function; get
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a6773c929642c5a180d0a8613435626e4:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	std::optional<T> get() const



.. rubric:: Returns:

A copy of the value, or std::nullopt after expiration or binding reset.

.. index:: pair: function; set
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1ad5430dfed908af7dcfd45fade14e98b5:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	bool set(const T& value) const



.. rubric:: Returns:

true when the live property was assigned ``value``.

.. index:: pair: function; observe
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1adcba8e59c867a6c61cabb249cca517fe:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	:ref:`Connection<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1a34371cd28009360162b4b58dec06d129>` observe(:ref:`Callback<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1af0b2199933de7f6ad187c5240e065ad9>` callback) const



.. rubric:: Returns:

A scoped value observer connection, or an empty connection after expiration.

.. index:: pair: function; observeLifetime
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a2914c8d1a46d79de130c4b7a53b948eb:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	:ref:`ObservableValue<doxid-class_e_e_1_1_observable_value>`<bool>:::ref:`Connection<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1a34371cd28009360162b4b58dec06d129>` observeLifetime(:ref:`ObservableValue<doxid-class_e_e_1_1_observable_value>`<bool>:::ref:`Callback<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1af0b2199933de7f6ad187c5240e065ad9>` callback) const



.. rubric:: Returns:

A scoped connection notified when the property is about to expire.

.. index:: pair: function; observeValidation
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1aaee4f0ab7c50d99c4e8bc219ef6ad140:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	:ref:`ValidationConnection<doxid-class_e_e_1_1_u_i_1_1_u_i_property_1a9625ca3d0a1d23aa97c50a389db64924>` observeValidation(:ref:`UIValueValidationState::Callback<doxid-class_e_e_1_1_u_i_1_1_u_i_value_validation_state_1a7f90f7554ee6794307c5554625bc24b0>` callback) const



.. rubric:: Returns:

A scoped validation observer, or an empty connection after expiration.

.. index:: pair: function; validation
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a3426744432ff5d2d0ed6f474c4395be3:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	:ref:`UIValueValidationResult<doxid-struct_e_e_1_1_u_i_1_1_u_i_value_validation_result>` validation() const



.. rubric:: Returns:

Current validation, or success after expiration.

.. index:: pair: function; validationEmitter
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a900f7885e7e12a6ad429319e4ec8189c:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	:ref:`UIWidget<doxid-class_e_e_1_1_u_i_1_1_u_i_widget>`* validationEmitter() const



.. rubric:: Returns:

The widget that produced the current input error, or nullptr.

.. index:: pair: function; widgets
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1abb19baeada56beb79b2f0c3fe883cc5d:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	std::vector<:ref:`UIWidget<doxid-class_e_e_1_1_u_i_1_1_u_i_widget>`*> widgets() const



.. rubric:: Returns:

All currently connected widgets, or an empty vector after expiration.

.. index:: pair: function; appendWidgets
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1ace3e7add749eadea1ff8dfd3d8ab25f7:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	template <typename Container>
	void appendWidgets(:ref:`Container<doxid-class_e_e_1_1_system_1_1_container>`& destination) const

Appends connected widgets without creating an intermediate collection.

.. index:: pair: function; forEachWidget
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a924636c013288d500876acbf2e8790ea:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	template <typename WidgetCallback>
	void forEachWidget(WidgetCallback&& callback) const

Invokes ``callback`` for every connected widget without allocating a collection.

.. index:: pair: function; firstEnabledWidget
.. _doxid-class_e_e_1_1_u_i_1_1_u_i_property_1_1_weak_handle_1a1c11e990552248863a74662321772bfd:

.. ref-code-block:: cpp
	:class: doxyrest-title-code-block

	:ref:`UIWidget<doxid-class_e_e_1_1_u_i_1_1_u_i_widget>`* firstEnabledWidget() const



.. rubric:: Returns:

The first enabled connected widget, or nullptr.