tt::detail::observable_base< T > Class Template Reference

#include <ttauri/observable.hpp>

Inheritance diagram for tt::detail::observable_base< T >:

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_base (observable_base const &)=delete
	observable_base (observable_base &&)=delete
observable_base &	operator= (observable_base const &)=delete
observable_base &	operator= (observable_base &&)=delete
	observable_base (observable< value_type > *owner) noexcept
	Constructor.
virtual value_type	load () const noexcept=0
	Get the current value.
virtual bool	store (value_type const &new_value) noexcept=0
	Set the value.
void	notify () noexcept
virtual void	replace_operand (observable_base *from, observable_base *to) noexcept
	Replace the operands.
void	replace_with (observable_base *other) noexcept
	Let other take over the listeners and owner.
void	add_listener (observable_base *listener)
void	remove_listener (observable_base *listener)

Detailed Description

template<typename T>
class tt::detail::observable_base< T >

Observable abstract base class.

Objects of the observable_base class will notify listeners through callbacks of changes of its value.

This class does not hold the value itself, concrete subclasses will either hold the value or calculate the value on demand. In many cases concrete subclasses may be sub-expressions of other observable objects.

This object will also track the time when the value was last modified so that the value can be animated. Usefull when displaying the value as an animated graphic element. For calculating inbetween values it will keep track of the previous value.

Constructor & Destructor Documentation

observable_base()

template<typename T >

tt::detail::observable_base< T >::observable_base ( observable< value_type > * owner )

inlinenoexcept

Constructor.

Member Function Documentation

load()

template<typename T >

virtual value_type tt::detail::observable_base< T >::load ( ) const

pure virtualnoexcept

Get the current value.

The value is often calculated directly from the cached values retrieved from notifications down the chain.

Implemented in tt::detail::observable_value< T >, and tt::detail::observable_chain< T >.

replace_operand()

template<typename T >

virtual void tt::detail::observable_base< T >::replace_operand ( observable_base< T > * from, observable_base< T > * to )

inlinevirtualnoexcept

Replace the operands.

Reimplemented in tt::detail::observable_chain< T >.

replace_with()

template<typename T >

void tt::detail::observable_base< T >::replace_with ( observable_base< T > * other )

inlinenoexcept

Let other take over the listeners and owner.

store()

template<typename T >

virtual bool tt::detail::observable_base< T >::store ( value_type const & new_value )

pure virtualnoexcept

Set the value.

The value is often not directly stored, but instead forwarded up the chain of observables. And then let the notifications flowing backward updated the cached values so that loads() will be quick.

Parameters

new_value

The new value

Returns

true if the value was different from before.

Implemented in tt::detail::observable_value< T >, and tt::detail::observable_chain< T >.

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

• hikogui/src/ttauri/observable.hpp