Skip to main content

Lambda patterns in C#?

I had few interesting discussions during the MVP Summit around using patterns from other programming languages in C#. Earlier, I’ve blogged about some of these scenarios.image

I’ve over heard Florian’s session this time during the summit, where he elaborated few interesting patterns from Java script that could be used in C#. He has a pretty good Code Project article regarding the same – Way To Lambda – and it is pretty good to see a formalized approach towards re-using these patterns in C#

One of my favorites is the C# version of Init-time branching (See Javascript Init time branching here)

   enum Mode
    {
        Http,
        WebSocket
    }

    class Messenger
    {

        public Func<string> Read { get; private set; }

        public Messenger(Mode m)
        {
            if (m == Mode.Http)
            {                
                Read = ()=>"Stub read logic using http"; 
            }
            else
            {
                Read = () => "Stub read logic using websocket";
            }
        }
    }

The above is a very simple version of Init time branching – but Instead of setting up the method (in this case the Read method) based on some configuration parameter, you can inject the same via the constructor or to the property – and in this way abstract out the branching as part the DI.

Convention Based Strategy Pattern *_*

Disclaimer: The remaining portion of the article is just not for regular use cases, and you can easily shoot yourself in the foot.

Now, let us use Init-Time branching to attain some kind of ‘Convention based’ strategy pattern. Branching will be done based on the caller’s semantics. Let us assemble a simple Serializer, that uses some convention based on the caller’s name. Note that we are using the Caller information attributes to extract the caller name.

class ConventionSerializer
    {
        public Func<string> Serialize { get; private set; }

        public ConventionSerializer([CallerMemberName] string memberName = "")
        {
            if (memberName.Contains("Xml"))
            {
                Serialize = () => 
                { /* serialize to xml */
                  return "xml"; 
                };
            }
            else
            {
                Serialize = () =>
                { /* serialize to json */
                    return "json";
                };
            }
        }

    }

And then, you may consume the same from the methods WriteXml and WriteJson.

       static void WriteXml()
        {
            var ser = new ConventionSerializer();
            Console.WriteLine(ser.Serialize()); //output xml
        }

        static void WriteJson()
        {
            var ser = new ConventionSerializer();
            Console.WriteLine(ser.Serialize()); //output json
        }

Was just bringing up an alternate perspective, requesting purists not to get offended. Happy Coding Smile

Popular posts from this blog

Creating a quick Todo listing app on Windows using IIS7, Node.js and Mongodb

As I mentioned in my last post, more and more organizations are leaning towards Web Oriented Architecture (WOA) which are highly scalable. If you were exploring cool, scalable options to build highly performing web applications, you know what Node.js is for.After following the recent post from Scott Hanselman, I was up and running quickly with Node.js. In this post, I’ll explain step by step how I’ve setup Node.js and Mongodb to create a simple Todo listing application.Setting up Node.jsThis is what I’ve done.1 – Goto http://nodejs.org/, scroll down and download node.exe for Windows, and place it in your c:\node folder2 – Goto IIS Node project in Git at https://github.com/tjanczuk/iisnode, download the correct ‘retail’ link of IIS Node zip file (I downloaded the already built retail package, otherwise you can download and build from the source).3 – Extract the zip file some where, and run the install.bat or install_iisexpress.bat depending on your IIS Version. If you don’t have IIS in…

Top 7 Coding Standards & Guideline Documents For C#/.NET Developers

Some time back, I collated a list of 7 Must Read, Free EBooks for .NET Developers, and a lot of people found it useful. So, I thought about putting together a list of Coding Standard guidelines/checklists for .NET /C# developers as well.As you may already know, it is easy to come up with a document - the key is in implementing these standards in your organization, through methods like internal trainings, Peer Reviews, Check in policies, Automated code review tools etc. You can have a look at FxCop and/or StyleCop for automating the review process to some extent, and can customize the rules based on your requirements.Anyway, here is a list of some good Coding Standard Documents. They are useful not just from a review perspective - going through these documents can definitely help you and me to iron out few hidden glitches we might have in the programming portion of our brain. So, here we go, the listing is not in any specific order.1 – IDesign C# Coding StandardsIDesign C# coding stand…

MVVM - Binding Multiple Radio Buttons To a single Enum Property in WPF

I had a property in my View Model, of an Enum type, and wanted to bind multiple radio buttons to this.

Firstly, I wrote a simple Enum to Bool converter, like this.

public class EnumToBoolConverter : IValueConverter { #region IValueConverter Members public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { if (parameter.Equals(value)) return true; else return false; } public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture) { return parameter; } #endregion }

And my enumeration is like

public enum CompanyTypes { Type1Comp, Type2Comp, Type3Comp } Now, in my XAML, I provided the enumeration as the ConverterParameter, of the Converter we wrote earlier, like
<Wi…