Create an event to watch for a change of variable

Question

Let's just say that I have:

public Boolean booleanValue;

public bool someMethod(string value)
{
   // Do some work in here.
   return booleanValue = true;
}

How can I create an event handler that fires up when the booleanValue has changed? Is it possible?

Answer 1

Avoid using public fields as a rule in general. Try to keep them private as much as you can. Then, you can use a wrapper property firing your event. See the example:

class Foo
{
    Boolean _booleanValue;

    public bool BooleanValue
    {
        get { return _booleanValue; }
        set
        {
            _booleanValue = value;
            if (ValueChanged != null) ValueChanged(value);
        }
    }

    public event ValueChangedEventHandler ValueChanged;
}

delegate void ValueChangedEventHandler(bool value);

That is one simple, "native" way to achieve what you need. There are other ways, even offered by the .NET Framework, but the above approach is just an example.

Answer 2

INotifyPropertyChanged is already defined to notify if property is changed.

Wrap your variable in property and use INotifyPropertyChanged interface.