Observer_Exercise.c

Go to the documentation of this file.

 
 
#include <stdio.h>
#include <stdlib.h>
 
#include "helpers/uint32_to_binary.h"
 
#include "Observer_NumberProducer.h"
#include "Observer_Exercise.h"
 
 
//=============================================================================
//=============================================================================
 
//=============================================================================
//=============================================================================
 
static void ObserverForDecimal_NumberChanged(uint32_t number)
{
    printf("    Decimal    : %u\n", number);
}
 
static void ObserverForHexadecimal_NumberChanged(uint32_t number)
{
    printf("    Hexadecimal: 0X%08X\n", number);
}
 
static void ObserverForBinary_NumberChanged(uint32_t number)
{
    char buffer[(sizeof(uint32_t) * 8) + 1];
    uint32_to_binary(number, buffer, sizeof(buffer));
    printf("    Binary     : %s\n", buffer);
}
 
 
//=============================================================================
//=============================================================================
 
// ! [Using Observer in C]
void Observer_Exercise(void)
{
    printf("\nObserver_Exercise\n");
 
    NumberProducer* producer = NumberProducer_Create(0);
 
    if (producer != NULL)
    {
        // Tell the number producer about the observers who are notified
        // whenever the value changes.
        bool subscribed = NumberProducer_SubscribeToNumberChanged(producer, ObserverForDecimal_NumberChanged);
        if (subscribed)
        {
            subscribed = NumberProducer_SubscribeToNumberChanged(producer, ObserverForHexadecimal_NumberChanged);
        }
        if (subscribed)
        {
            subscribed = NumberProducer_SubscribeToNumberChanged(producer, ObserverForBinary_NumberChanged);
        }
 
        // If everyone subscribed, trigger the observers
        if (subscribed)
        {
            // Call the number producer's Update() method a number of times.
            // The observers automatically print out the current value in
            // different bases.
            for (int index = 0; index < 10; ++index)
            {
                printf("  Update %d on number producer.  Results from observers:\n", index);
                NumberProducer_UpdateNumber(producer);
            }
        }
 
        // When done, remove the observers from the number producer.
        // It's always good to clean up after ourselves.
        NumberProducer_UnsubscribeFromNumberChanged(producer, ObserverForBinary_NumberChanged);
        NumberProducer_UnsubscribeFromNumberChanged(producer, ObserverForHexadecimal_NumberChanged);
        NumberProducer_UnsubscribeFromNumberChanged(producer, ObserverForDecimal_NumberChanged);
 
        NumberProducer_Destroy(producer);
        producer = NULL;
    }
 
    printf("  Done.\n");
}
// ! [Using Observer in C]