Represents the Subject in this example, in this case, a class that contains a single number that is updated with a call to the Update() method. Whenever Update() is called, the number is incremented and all observers are notified. The observers then fetch the current number via the INumberProducer interface. More...

#include <ObserverSubject_NumberProducer.h>

Inheritance diagram for ObserverSubject_NumberProducer:

Collaboration diagram for ObserverSubject_NumberProducer:

Public Member Functions
	ObserverSubject_NumberProducer ()
	Default constructor.

void	Update () override
	Update the number then notify all observers.

uint32_t	FetchNumber () override
	Observers call this method to fetch the current number.

void	SubscribeToNumberChanged (IObserverNumberChanged::shared_ptr_t observer)
	A client calls this to subscribe an observer to this class instance for notifications about changing numbers. Does nothing if the given observer is already subscribed.

void	UnsubscribeFromNumberChanged (IObserverNumberChanged::shared_ptr_t observer)
	A client calls this to unsubscribe an observer from this class instance so notifications are no longer received. Does nothing if the given observer was not subscribed.

Public Member Functions inherited from IEventNotifications
virtual	~IEventNotifications ()
	Virtual destructor required for interfaces in abstract classes.

virtual void	SubscribeToNumberChanged (IObserverNumberChanged::shared_ptr_t observer)=0

virtual void	UnsubscribeFromNumberChanged (IObserverNumberChanged::shared_ptr_t observer)=0

Public Member Functions inherited from INumberProducer
virtual	~INumberProducer ()
	Virtual destructor required for interfaces in abstract classes.

virtual void	Update ()=0
	Update the number then notify all observers.

virtual uint32_t	FetchNumber ()=0
	Return the current value from the Subject.

Private Types
using	ObserversList = std::vector< IObserverNumberChanged::shared_ptr_t >

Private Member Functions
void	_NotifyNumberChanged ()
	Helper method to notify all observers that the number has changed.

ObserversList::iterator	_FindObserver (const IObserverNumberChanged::shared_ptr_t &observer)
	Helper method to retrieve the iterator to the specified observer if the observer is in the list.

bool	_ContainsObserver (const IObserverNumberChanged::shared_ptr_t &observer)
	Helper method to determine if the specified observer is already present in the list of observers for this class.

Private Attributes
ObserversList	_observers
	The list of observers subscribed to this class instance.

uint32_t	_number
	The number being maintained.

Additional Inherited Members
Public Types inherited from INumberProducer
using	shared_ptr_t = std::shared_ptr< INumberProducer >
	Alias to make it easier to use this shared pointer.

Detailed Description

Represents the Subject in this example, in this case, a class that contains a single number that is updated with a call to the Update() method. Whenever Update() is called, the number is incremented and all observers are notified. The observers then fetch the current number via the INumberProducer interface.

Definition at line 143 of file ObserverSubject_NumberProducer.h.

Member Typedef Documentation

◆ ObserversList

using ObserversList = std::vector<IObserverNumberChanged::shared_ptr_t>

private

Definition at line 147 of file ObserverSubject_NumberProducer.h.

Constructor & Destructor Documentation

◆ ObserverSubject_NumberProducer()

ObserverSubject_NumberProducer ( )

inline

Default constructor.

Definition at line 212 of file ObserverSubject_NumberProducer.h.

Member Function Documentation

◆ _ContainsObserver()

bool _ContainsObserver ( const IObserverNumberChanged::shared_ptr_t & observer )

inlineprivate

Helper method to determine if the specified observer is already present in the list of observers for this class.

Parameters

observer An observer to look for.

Returns: Returns true if the observer is on this class's list of observers; otherwise, returns false.

Definition at line 201 of file ObserverSubject_NumberProducer.h.

References ObserverSubject_NumberProducer::_FindObserver(), and ObserverSubject_NumberProducer::_observers.

Referenced by ObserverSubject_NumberProducer::SubscribeToNumberChanged(), and ObserverSubject_NumberProducer::UnsubscribeFromNumberChanged().

◆ _FindObserver()

ObserversList::iterator _FindObserver ( const IObserverNumberChanged::shared_ptr_t & observer )

inlineprivate

Helper method to retrieve the iterator to the specified observer if the observer is in the list.

Parameters

observer An observer to look for.

Returns: Returns an iterator to the found observer; otherwise, returns std::end(_observers).

Definition at line 187 of file ObserverSubject_NumberProducer.h.

References ObserverSubject_NumberProducer::_observers.

Referenced by ObserverSubject_NumberProducer::_ContainsObserver(), and ObserverSubject_NumberProducer::UnsubscribeFromNumberChanged().

◆ _NotifyNumberChanged()

void _NotifyNumberChanged ( )

inlineprivate

Helper method to notify all observers that the number has changed.

Definition at line 164 of file ObserverSubject_NumberProducer.h.

References ObserverSubject_NumberProducer::_observers.

Referenced by ObserverSubject_NumberProducer::Update().

◆ FetchNumber()

uint32_t FetchNumber ( )

inlineoverridevirtual

Observers call this method to fetch the current number.

Returns: Returns the current number.

Implements INumberProducer.

Definition at line 236 of file ObserverSubject_NumberProducer.h.

References ObserverSubject_NumberProducer::_number.

◆ SubscribeToNumberChanged()

void SubscribeToNumberChanged ( IObserverNumberChanged::shared_ptr_t observer )

inlinevirtual

A client calls this to subscribe an observer to this class instance for notifications about changing numbers. Does nothing if the given observer is already subscribed.

Parameters

observer An observer represented by the IObserverNumberChanged interface.

In a multi-threaded environment, this method would use a lock of some form. This example doesn't use multiple threads so no lock is needed. See the HandlerChain::SendMessage() method in HandlerChain_Class.cpp for an example of such a lock.

Implements IEventNotifications.

Definition at line 258 of file ObserverSubject_NumberProducer.h.

References ObserverSubject_NumberProducer::_ContainsObserver(), and ObserverSubject_NumberProducer::_observers.

◆ UnsubscribeFromNumberChanged()

void UnsubscribeFromNumberChanged ( IObserverNumberChanged::shared_ptr_t observer )

inlinevirtual

A client calls this to unsubscribe an observer from this class instance so notifications are no longer received. Does nothing if the given observer was not subscribed.

Parameters

observer An observer represented by the IObserverNumberChanged interface.

In a multi-threaded environment, this method would use a lock of some form. This example doesn't use multiple threads so no lock is needed. See the HandlerChain::SendMessage() method in HandlerChain_Class.cpp for an example of such a lock.

Implements IEventNotifications.

Definition at line 279 of file ObserverSubject_NumberProducer.h.

References ObserverSubject_NumberProducer::_FindObserver(), and ObserverSubject_NumberProducer::_observers.