Question

I want enqueue a list of tasks and then perform on certain event. Code:

internal class MyClass
{
    private Queue<Task> m_taskQueue;

    protected MyClass()
    {
        m_taskQueue = new Queue<Task>();
    }

    public delegate bool Task(object[] args);

    public void EnqueueTask(Task task)
    {
        m_taskQueue.Enqueue(task);
    }

    public virtual bool Save()
    {
        // save by processing work queue
        while (m_taskQueue.Count > 0)
        {
            var task = m_taskQueue.Dequeue(); 
            var workItemResult = task.Invoke();

            if (!workItemResult) 
            {
                // give up on a failure
                m_taskQueue.Clear();
                return false;
            }                
        }
        return true;
    }
}

Each delegate task may have their own list of parameters: Task(object[] args). My question is how to pass the parameter to each task for the task queue?

Answer 1

Okay, now we have a bit more information, it sounds like your EnqueueTask method should actually look like this:

public void EnqueueTask(Task task, object[] values)

Right?

For starters I would avoid using the name Task, which is already part of the core of .NET 4 and will become very prominent in .NET 5. As Joshua said, you’ve basically got a Func<object[], bool>.

Next, you could keep two lists – one for the delegates and one for the values, but it’s easier just to keep a Queue<Func<bool>> like this:

private readonly Queue<Func<bool>> taskQueue = new Queue<Func<bool>>();


public void EnqueueTask(Task task, object[] values)
{
    taskQueue.Enqueue(() => task(values));
}

Then the rest of your code will actually work “as is”. The lambda expression there will capture values and task, so when you invoke the Func<bool>, it will supply those values to the original delegate.