Patrón para ejecución de procesos largos con notificación-actualización de UI de resultados parciales

gistfile1.cs

//Ambas soluciones estan propuestas por Jorge Fioranelli: jorge.fioranelli@gmail.com


public interface IStep
{
    event EventHandler<StepEventArgs> Started;
    event EventHandler<StepEventArgs> Finished;
    void Execute();
}

public class StepEventArgs : EventArgs
{
    public string Message { get; set; }
}

public class StepA : IStep
{
    public event EventHandler<StepEventArgs> Started;
    public event EventHandler<StepEventArgs> Finished;
    public void Execute()
    {
        OnStarted(new StepEventArgs{ Message = "Paso A Iniciado" });

        // Ejecutar las acciones del Paso A aqui
        OnFinished(new StepEventArgs{ Message = "Paso A Finalizado" });
    }

    protected virtual void OnStarted(StepEventArgs args)
    {
        if(Started != null)
            Started(this, args);
    }

    protected virtual void OnFinished(StepEventArgs args)
    {
        if(Finished != null)
            Finished(this, args);
    }
}

public class StepB : IStep
{
    public event EventHandler<StepEventArgs> Started;
    public event EventHandler<StepEventArgs> Finished;
    public void Execute()
    {
        OnStarted(new StepEventArgs{ Message = "Paso B Iniciado" });

        // Ejecutar las acciones del Paso B aqui
        OnFinished(new StepEventArgs{ Message = "Paso B Finalizado" });
    }

    protected virtual void OnStarted(StepEventArgs args)
    {
        if(Started != null)
            Started(this, args);
    }

    protected virtual void OnFinished(StepEventArgs args)
    {
        if(Finished != null)
            Finished(this, args);
    }
}

public class Engine
{
    public IEnumerable<IStep> Steps
    {
        get
        {
            yield return new StepA();
            yield return new StepB();
        }
    }

    public void ExecuteSteps()
    {
        foreach (var step in Steps)
        {
            step.Started += Step_Started;
            step.Finished += Step_Finished;

            step.Execute();

            step.Started -= Step_Started;
            step.Finished -= Step_Finished;
        }
    }

    void Step_Started(object sender, StepEventArgs e)
    {
        Console.WriteLine(e.Message);
    }

    void Step_Finished(object sender, StepEventArgs e)
    {
        Console.WriteLine(e.Message);
    }
}

Otra solucion seria:

public interface ILogger
{
    void WriteMessage(string message);
}

public class ConsoleLogger : ILogger
{
    public void WriteMessage(string message)
    {
        Console.WriteLine(message);
    }
}

public class StepA
{
    private readonly ILogger logger;

    public StepA(ILogger logger)
    {
        this.logger = logger;
    }

    public void Execute()
    {
        logger.WriteMessage("Paso A Iniciado");

        // Executar las acciones del paso A aqui

        logger.WriteMessage("Paso A Finalizado");
    }

}