Yield keyword in .NET

fransiscuss — Sun, 20 May 2012 23:35:15 +0000

I believe some of you already know about this but for me I never used it. Yield keyword has been existed since .NET 2.0 so I decided to look up of what it does and try to understand it

Based on MSDN

Yield is used in an iterator block to provide a value to the enumerator object or to signal the end of iteration, it takes one of the following form

Based on my understanding

Yield is a concatenation for a collection, or in SQL we normally use UNION

Yield break; is used to exit from the concatenation (remember it is not used to skip !)

One practical sample that I can think of is to get the enumerable of exception from inner exception (e.g stack trace)

sample code

Code Snippet

class Program
    {
        ///
        /// simple function to return IEnumerable of integer
        ///
        ///
        private static IEnumerable<int> GetIntegers()
        {
            for (int i = 0; i <= 10; i++)
                yield return i;
        }
        ///
        /// simple function to return collection of class
        ///
        ///
        private static IEnumerable<MyClass> GetMyNumbers()
        {
            for (int i = 0; i <= 10; i++)
                if (i > 5)
                    yield break;
                else
                    yield return new MyClass() { Number = i };
        }
        internal class MyClass
        {
            public int Number { get; set; }
            public string PrintNumber
            {
                get {
                    return “This is no “ + Number.ToString();
                }
            }
        }
        static void Main(string[] args)
        {
            Console.WriteLine(“Simple array of integer”);
            foreach (var number in GetIntegers())
                Console.WriteLine(number.ToString());
            Console.WriteLine();
            Console.WriteLine(“Collection of classes”);
            foreach (var myclass in GetMyNumbers())
                Console.WriteLine(myclass.PrintNumber);
            Console.ReadLine();
        }
    }

Output

Simple array of an integer
0
1
2
3
4
5
6
7
8
9
10Collection of classes
This is no 0
This is no 1
This is no 2
This is no 3
This is no 4
This is no 5

Remapping svc extension in IIS 7 extension handlers

fransiscuss — Tue, 08 Nov 2011 03:55:45 +0000

If you open your WCF/ svc file in your localhost through browser and it just display blank page then what might happen is you don’t have handler associated with svc extension

To verify it, go to your IIS and go to IIS Handler Mappings and try to find an svc extension entry, but if you couldn’t find extension SVC exists on the list, then you can remap/re-add the svc extension by running

C:\Windows\Microsoft.NET\Framework64\v3.0\Windows Communication Foundation\ServiceModelReg.exe –i

*if you are still using 32 bit then you just need to replace Framework64 with Framework

Fransiscus Setiawan » .NET

Yield keyword in .NET

Remapping svc extension in IIS 7 extension handlers