Declaration of the NumberProducer structure along with its support functions, NumberProducer_Create(), NumberProducer_Destroy(), NumberProducer_SubscribeToNumberChanged(), NumberProducer_UnsubscribeFromNumberChanged(), and NumberProducer_UpdateNumber(), as used in the Observer Pattern. More...

#include "Observer_NumberChangedFunctionList.h"

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Classes
struct	NumberProducer
	Represents the Subject in this example. In this case, a structure that contains a list of observers and a single number that is updated. When the NumberProducer_UpdateNumber() function is called, the number is incremented and all observers are notified. The observers are passed the changed number. More...

Macros
#define	__OBSERVER_NUMBERPRODUCER_H__

Functions
NumberProducer *	NumberProducer_Create (uint32_t number)
	Create an instance of the NumberProducer structure and initialize the structure with the specified number.

void	NumberProducer_Destroy (NumberProducer *producer)
	Destroy the given instance of a NumberProducer object. After this function returns, the pointer to the NumberProducer instance is no longer valid.

bool	NumberProducer_SubscribeToNumberChanged (NumberProducer *producer, NumberChangedFunction observer)
	Subscribe to the given NumberProducer to received changes to that producer's number. Does nothing if the given observer is already subscribed.

void	NumberProducer_UnsubscribeFromNumberChanged (NumberProducer *producer, NumberChangedFunction observer)
	Unsubscribe from the Given NumberProducer so the given observer will no longer be called when the producer's number is changed.

void	NumberProducer_UpdateNumber (NumberProducer *producer)
	Update the number in the given NumberProducer object, triggering a call to all observer in the producer.

Detailed Description

Declaration of the NumberProducer structure along with its support functions, NumberProducer_Create(), NumberProducer_Destroy(), NumberProducer_SubscribeToNumberChanged(), NumberProducer_UnsubscribeFromNumberChanged(), and NumberProducer_UpdateNumber(), as used in the Observer Pattern.

Definition in file Observer_NumberProducer.h.

Macro Definition Documentation

◆ __OBSERVER_NUMBERPRODUCER_H__

#define __OBSERVER_NUMBERPRODUCER_H__

Definition at line 11 of file Observer_NumberProducer.h.

Function Documentation

◆ NumberProducer_Create()

NumberProducer * NumberProducer_Create ( uint32_t number )

Create an instance of the NumberProducer structure and initialize the structure with the specified number.

Parameters

number The number to start off with.

Returns: Returns a pointer to a NumberProducer object if successful; otherwise, returns NULL, indicating an out of memory condition (or a NULL argument).

Definition at line 54 of file Observer_NumberProducer.c.

References NumberProducer::number.

Referenced by Observer_Exercise().

◆ NumberProducer_Destroy()

void NumberProducer_Destroy ( NumberProducer * producer )

Destroy the given instance of a NumberProducer object. After this function returns, the pointer to the NumberProducer instance is no longer valid.

Parameters

producer The NumberProducer object to destroy.

Definition at line 73 of file Observer_NumberProducer.c.

References NumberChangedFunctionList_Clear(), and NumberProducer::observerList.

Referenced by Observer_Exercise().

◆ NumberProducer_SubscribeToNumberChanged()

bool NumberProducer_SubscribeToNumberChanged	(	NumberProducer *	producer,
		NumberChangedFunction	observer
	)

Subscribe to the given NumberProducer to received changes to that producer's number. Does nothing if the given observer is already subscribed.

Parameters

producer	The NumberProducer object to subscribe to.
observer	A function to be called when the producer's number changes.

Returns: Returns true if the subscribe operation succeeded; otherwise, returns false, indicating an out of memory condition (or a NULL argument was passed in).

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.

Definition at line 85 of file Observer_NumberProducer.c.

References NumberChangedFunctionList_Add(), NumberChangedFunctionList_Find(), and NumberProducer::observerList.

Referenced by Observer_Exercise().