tt::observable< T > Class Template Reference

#include <ttauri/observable.hpp>

Public Types
using	value_type = T
using	notifier_type = notifier<void()>
using	callback_type = typename notifier_type::callback_type
using	callback_ptr_type = typename notifier_type::callback_ptr_type

Public Member Functions
	observable (observable &&other) noexcept
observable &	operator= (observable &&other) noexcept
	observable (observable const &other) noexcept
observable &	operator= (observable const &other) noexcept
	observable () noexcept
	Default construct a observable holding a default constructed value.
	observable (value_type const &value) noexcept
	Construct a observable holding value.
	operator bool () const noexcept
	Is the internal value true.
observable &	operator= (value_type const &value) noexcept
	Assign a new value.
observable &	operator+= (value_type const &value) noexcept
	Inplace add a value.
observable &	operator-= (value_type const &value) noexcept
	Inplace subtract a value.
value_type	load () const noexcept
	Load the value.
value_type	operator* () const noexcept
	Load the value.
bool	store (value_type const &new_value) noexcept
	Assign a new value.
template<typename Callback > requires (std::is_invocable_v<Callback>)
callback_ptr_type	subscribe (Callback &&callback) noexcept
	Subscribe a callback function.
callback_ptr_type	subscribe (callback_ptr_type const &callback) noexcept
	Subscribe a callback function.
void	unsubscribe (callback_ptr_type const &callback_ptr) noexcept
	Unsubscribe a callback function.
value_type	operator- () const noexcept
	Negate and return the value.

Friends
class	detail::observable_base< value_type >
bool	operator== (observable const &lhs, observable const &rhs) noexcept
	Compare the value of two observables.
bool	operator== (observable const &lhs, value_type const &rhs) noexcept
	Compare and observable with a value.
bool	operator== (value_type const &lhs, observable const &rhs) noexcept
	Compare and observable with a value.
auto	operator<=> (observable const &lhs, observable const &rhs) noexcept
	Compare the value of two observables.
auto	operator<=> (observable const &lhs, value_type const &rhs) noexcept
	Compare and observable with a value.
auto	operator<=> (value_type const &lhs, observable const &rhs) noexcept
	Compare and observable with a value.
auto	operator+ (observable const &lhs, observable const &rhs) noexcept
	Add the value of two observables.
auto	operator+ (observable const &lhs, value_type const &rhs) noexcept
	Add the value of observables to a value.
auto	operator+ (value_type const &lhs, observable const &rhs) noexcept
	Add the value of observables to a value.
auto	operator- (observable const &lhs, observable const &rhs) noexcept
	Subtract the value of two observables.
auto	operator- (observable const &lhs, value_type const &rhs) noexcept
	Subtract a value from an observable to a value.
auto	operator- (value_type const &lhs, observable const &rhs) noexcept
	Subtract an observable value from a value.

Detailed Description

template<typename T>
class tt::observable< T >

An observable value.

An observable-value will notify listeners when a value changes. An observable-value can also observe another observable-value.

For widgets this allows changes to values to be reflected on the screen in multiple places. Or values to be written automatically to a configuration file.

Constructor & Destructor Documentation

observable() [1/2]

template<typename T >

tt::observable< T >::observable ( )

inlinenoexcept

Default construct a observable holding a default constructed value.

observable() [2/2]

template<typename T >

tt::observable< T >::observable ( value_type const & value )

inlinenoexcept

Construct a observable holding value.

Parameters

value

The value to set the internal value to.

Member Function Documentation

load()

template<typename T >

value_type tt::observable< T >::load ( ) const

inlinenoexcept

Load the value.

Loads the internal or observed value.

Returns

The internal or observed value.

operator bool()

template<typename T >

tt::observable< T >::operator bool ( ) const

inlineexplicitnoexcept

Is the internal value true.

operator*()

template<typename T >

value_type tt::observable< T >::operator* ( ) const

inlinenoexcept

Load the value.

Loads the internal or observed value.

Returns

The internal or observed value.

operator+=()

template<typename T >

observable & tt::observable< T >::operator+= ( value_type const & value )

inlinenoexcept

Inplace add a value.

Updates the internal value or the value that is being observed non-atomically.

Parameters

value

The value to add.

Returns

*this.

Postcondition

Listeners will be notified.

operator-()

template<typename T >

value_type tt::observable< T >::operator- ( ) const

inlinenoexcept

Negate and return the value.

Returns

The negative of the internal or observed value.

operator-=()

template<typename T >

observable & tt::observable< T >::operator-= ( value_type const & value )

inlinenoexcept

Inplace subtract a value.

Updates the internal value or the value that is being observed non-atomically.

Parameters

value

The value to subtract.

Returns

*this.

Postcondition

Listeners will be notified.

operator=()

template<typename T >

observable & tt::observable< T >::operator= ( value_type const & value )

inlinenoexcept

Assign a new value.

Updates the internal value or the value that is being observed.

Parameters

value

The value to assign.

Returns

*this.

Postcondition

Listeners will be notified.

store()

template<typename T >

bool tt::observable< T >::store ( value_type const & new_value )

inlinenoexcept

Assign a new value.

Updates the internal value or the value that is being observed.

Parameters

value

The value to assign.

Returns

*this.

Postcondition

Listeners will be notified.

subscribe() [1/2]

template<typename T >

template<typename Callback >
requires (std::is_invocable_v<Callback>)

callback_ptr_type tt::observable< T >::subscribe ( Callback && callback )

inlinenoexcept

Subscribe a callback function.

The subscribed callback function will be called when the value is modified.

Template Parameters

Callback

A callback-type of the form void().

Parameters

callback

The callback function to subscribe.

Returns

A std::shared_ptr to the callback function.

Postcondition

A std::weak_ptr to the callback function is retained by the observable. When this pointer is expired the callback will be automatically unsubscribed.

subscribe() [2/2]

template<typename T >

callback_ptr_type tt::observable< T >::subscribe ( callback_ptr_type const & callback )

inlinenoexcept

Subscribe a callback function.

The subscribed callback function will be called when the value is modified.

Parameters

callback

The callback function to subscribe.

Returns

A std::shared_ptr to the callback function.

Postcondition

A std::weak_ptr to the callback function is retained by the observable. When this pointer is expired the callback will be automatically unsubscribed.

unsubscribe()

template<typename T >

void tt::observable< T >::unsubscribe ( callback_ptr_type const & callback_ptr )

inlinenoexcept

Unsubscribe a callback function.

Parameters

callback

The callback function to subscribe.

Friends And Related Symbol Documentation

operator+ [1/3]

template<typename T >

auto operator+ ( observable< T > const & lhs, observable< T > const & rhs )

friend

Add the value of two observables.

Parameters

lhs	An observable-value
rhs	An observable-value

Returns

The sum of the internal or observed value of lhs and rhs.

operator+ [2/3]

template<typename T >

auto operator+ ( observable< T > const & lhs, value_type const & rhs )

friend

Add the value of observables to a value.

Parameters

lhs	An observable-value
rhs	A value

Returns

The sum of the internal or observed value of lhs and rhs.

operator+ [3/3]

template<typename T >

auto operator+ ( value_type const & lhs, observable< T > const & rhs )

friend

Add the value of observables to a value.

Parameters

lhs	A value
rhs	An observable-value

Returns

The sum of lhs with the internal or observed value of rhs.

operator- [1/3]

template<typename T >

auto operator- ( observable< T > const & lhs, observable< T > const & rhs )

friend

Subtract the value of two observables.

Parameters

lhs	An observable-value
rhs	An observable-value

Returns

The difference between of the internal or observed value of lhs and rhs.

operator- [2/3]

template<typename T >

auto operator- ( observable< T > const & lhs, value_type const & rhs )

friend

Subtract a value from an observable to a value.

Parameters

lhs	An observable-value
rhs	A value

Returns

The different between the internal or observed value of lhs and rhs.

operator- [3/3]

template<typename T >

auto operator- ( value_type const & lhs, observable< T > const & rhs )

friend

Subtract an observable value from a value.

Parameters

lhs	A value
rhs	An observable-value

Returns

The difference between the lhs and the internal or observed value of rhs.

operator<=> [1/3]

template<typename T >

auto operator<=> ( observable< T > const & lhs, observable< T > const & rhs )

friend

Compare the value of two observables.

Parameters

lhs	An observable-value.
rhs	An observable-value.

Returns

True the comparison result of the internal or observed value of both lhs and rhs.

operator<=> [2/3]

template<typename T >

auto operator<=> ( observable< T > const & lhs, value_type const & rhs )

friend

Compare and observable with a value.

Parameters

lhs	An observable-value.
rhs	A value.

Returns

The comparison result between the internal or observed value of lhs and the rhs.

operator<=> [3/3]

template<typename T >

auto operator<=> ( value_type const & lhs, observable< T > const & rhs )

friend

Compare and observable with a value.

Parameters

lhs	A value.
rhs	An observable-value.

Returns

The comparison result between the lhs and to the internal or observed value of rhs.

operator== [1/3]

template<typename T >

bool operator== ( observable< T > const & lhs, observable< T > const & rhs )

friend

Compare the value of two observables.

Parameters

lhs	An observable-value.
rhs	An observable-value.

Returns

True if the internal or observed value of both lhs and rhs are equal.

operator== [2/3]

template<typename T >

bool operator== ( observable< T > const & lhs, value_type const & rhs )

friend

Compare and observable with a value.

Parameters

lhs	An observable-value.
rhs	A value.

Returns

True if the internal or observed value of lhs is equal to rhs.

operator== [3/3]

template<typename T >

bool operator== ( value_type const & lhs, observable< T > const & rhs )

friend

Compare and observable with a value.

Parameters

lhs	A value.
rhs	An observable-value.

Returns

True if lhs is equal to the internal or observed value of rhs.

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The documentation for this class was generated from the following file:

• hikogui/src/ttauri/observable.hpp