Using background threads for long processes in MFC: Sidebar: The Task

// task.h
class TaskObserver;

class Task
{
    TaskObserver *m_pObserver;

public:
    Task(TaskObserver *pObserver)
        : m_pObserver(pObserver) { }

    void Run();

private:
    inline void ReportProgress(int current, int maximum);
};

class TaskObserver
{
public:
    virtual void OnProgress(int current, int maximum) = 0;
};

inline void Task::ReportProgress(int current, int maximum)
{
    if (m_pObserver)
        m_pObserver->OnProgress(current, maximum);
}

// task.cpp
#include "StdAfx.h"
#include "task.h"

void Task::Run()
{
    // Pretend to do some work.
    const int MAX_ITERATIONS = 10;
    for (int i = 0; i < MAX_ITERATIONS; ++i)
    {
        ReportProgress(i, MAX_ITERATIONS);
        Sleep(1000);
    }

    ReportProgress(MAX_ITERATIONS, MAX_ITERATIONS);
}