Slides from DCI talk at ANUG

I did a talk on DCI at my local .NET User Group, ANUG, the other night and had a great time. The slides from the talk were:

DCI ANUG - 24th November 2010

View more presentations from c_horsdal.

The slides were followed by three demos:

1. A simple Scala example "cross"-compiled to run on .NET
2. A simple Ruby example running on IronRuby
3. A slightly larger ASP.NET MVC based C# example, which I will be posting details about in the furture.

Upcoming events

I just wanted to point to 2 events that are coming up soon that I am participating in:

1. I am doing a talk on DCI in the Aarhus .NET User Group on the 24th of November 2010. Register at  http://on.fb.me/9QOa3s 
2. I am participating in Random Hacks of Kindness during the weekend 4th and 5th of December 2010. More info and registration at: http://rhokaarhus.eventbrite.com/ 

A Pinch of Functional in my C# - An Everyday Example

I'm working on a codebase that, like many other code bases,  has a number of data access objects(DAOs) that all inherit a common superclass. The other day I got tired of looking this pattern of code repeated a lot in the DAOs:

    1        public MyDTO GetMyDTO(...)

    2         {

    3             DataContext DB = NewDBContext;

    4             try

    5             {

    6                 DB.Connection.Open();

    7                 //Fetch something from the DB and return it

    8             }

    9             finally

   10             {

   11                 if (DB.Connection.State == ConnectionState.Open)

   12                     DB.Connection.Close();

   13             }

   14         }

I wanted the creation of the DBContext and the handling of the connection to be factored into somewhere reusable. So I applied the functional "suround with" pattern and introduced this method in the superclass:

    1        protected TReturn UsingDBConnection<TReturn>(Func<DataContext, TReturn> func)

    2         {

    3             DataContext DB = NewDBContext;

    4             try

    5             {

    6                 DB.Connection.Open();

    7                 return func(DB);

    8             }

    9             finally

   10             {

   11                 if (DB.Connection.State == ConnectionState.Open)

   12                     DB.Connection.Close();

   13             }

   14         }

and the DAO code then turns into this:

    1        public MyDTO GetMyDTO(...)

    2         {

    3             return UsingDBConnection(DB =>

    4             {

    7                 //Fetch something from the DB and return it

    7             });

    8         }

C# has supported this for years now, so why am I posting it? -Because I wish I saw more of this type of code. To me it's easy to read and I get to reuse the common part.