Question

I’m making a WP7-app for my programming class and I want to implement a callback function for checking the state of an integer and not calling the function for checking it explicitly. The integer iterates at the push of a button and when it reaches it’s max input I would like to have a callback function checking this, but I’m not completely sure how to implement it.

private void Right_Button_Click(object sender, RoutedEventArgs e)
    {
        if (current_input <= MAX_INPUT)
        {
            user_input[current_input] = 3;
            current_input++;
            display_result();
        }

    }

    #endregion

    void display_result()
    {
        //will move alot of this to the a result page
        DateTime time_end = DateTime.Now;
        TimeSpan difference = time_end.Subtract(timer);
        time_stamp = difference.ToString();
        bool combination_error = true;
        if (current_input == 4)
        {
            for (int i = 0; i < MAX_INPUT; i++)
            {
                if (user_input[i] != combination[i])
                {
                    combination_error = false;
                    break;
                }
            }

            if (combination_error)
            {
                MessageBox.Show("Correct combination The timer is " + time_stamp);
            }
            else
            {
                MessageBox.Show("Wrong combination");
            }
        }
    }

It’s after I increment current_input that I now explicitly call display result something I wish not to do and instead create a callback function for it.

Answer 1

You can’t really put a callback function on an integer, however, you could expose your integer as a property and call a function from the property setter. Look at this example:

private int _myInteger = 0;

private int MyInteger {
    get
    {
         return _myInteger;
    } 
    set 
    {
        _myInteger = value;
        if (_myInteger <= MAX_INPUT)
            MyCallBackFunction();
    }
}

private void Right_Button_Click(object sender, RoutedEventArgs e)
{
    MyInteger = MyInteger + 1;
    // Do your other stuff here
}

private void MyCallBackFunction()
{
    // This function executes when your integer is <= MAX_VALUE
    // Do Whatever here
    display_result();
}

What this is doing is exposing your integer through a private property. As long as you set the property through the setter (e.g. use the MyInteger = MyInteger + 1; syntax), you can have your setter check the condition and execute your call back function.