Sometime back I had blogged about whether programmers really use anonymous methods. Recently I found a problem for which anonymous method felt like a natural choice.

I am currently coding an UI glue layer. I need it because I have some stable back-end code (with event-handlers) which I have to tie with some new UI. The problem is that the event handler signatures of the backend matches some other UI technology that was used before (which I cannot modify). The signature doesn't match the one required by the UI technology I'm glueing it to. Interestingly these handlers were not added using += but using some methods which got the handler as a parameter.

The first solution that comes to mind is to change the method that adds the handler so that it creates an instance of some adapter class. The adapter class has [in] and [out] event handlers. The [in] handler matches the new UI-technology specific signature and the [out] matches the older signature. Objects of this class is created by the API and the [in] handler is tied to the UI-events and when it gets fired it simply calls the [out] handler.

The problem with this approach is defining all the adapter classes and coding them up. Anonymous methods with outter variable reference solves this problem elegantly.

public override object AddFocusChangeEventHandler(MyEventHandler eventHandler)
{
    UISpecificEventHandler uiHandler = 
        delegate(object sender, UISpecficEventArgs e)
        {
            // Convert sender and UISpecificEventArgs to what
            // matches MyEventHandler and call it. 
           eventHandler(converterSender, convertedArgs);
        };
    UI.AddFocusChangedEventHandler(uiHandler );
    return uiHandler;
}

With this I'm easily done as C# automatically generates hidden classes to wrap the anonymous method when there is a reference to an outter variable (variable defined outside the anonymous method, eventHandler in this case).

Yesterday on our post-lunch walk (we take a brisk walk around the campus after lunch when its not too hot) we were discussing phone numbers. Cell phone numbers in India are 10 digits long. Remembering numbers have become difficult, specially so for your own number because you never dial it yourself!!!

So I asked everyone around to guess how I remember it....

I don't, I just store it as this on the phone. What else do you expect from a C# programmer???

I went to a place of worship in Hyderabad where I saw this peculiar machine. I don't know what to call it!! Its a electrical machine that plays the drum and bells (??). I just couldn't figure out why they couldn't use a music player instead. Unfortunately (or was it fortunately??) it was powered off at that moment.