Let's learn Dictionary Initializer of C# 6.0

Introduction

The Dictionary Initializer was introduce in C#6.0, Visual Studio 2015 and .NET 4.6. By using this, we can map the indexer at the time of dictionary object initialization. In this article, we will look into how to use the same with an example.

Straight to experiment

Object creation

Let us first create two classes say Class1 and Class2 as under

internal class Class1
{
    public string ClassMethod()
    {
        return "From Class 1";
    }
}
internal class Class2
{
    public string ClassMethod()
    {
        return "From Class 2";
    }
} 

Add the objects to the Dictionary by using the new C# 6.0 Dictionary Initializer way

Then create a Dictionary Initializer as under

private static Dictionary<string, Type> ObjectTypes()
{

    return new Dictionary<string, Type>
    {
        ["Class1"] = typeof(Class1),
        ["Class2"] = typeof(Class2)               
    };
}

Prior to C#6.0, we used to use the dictionary initializer to initialize dictionary objects with key and values as shown below

private static Dictionary<string, Type> ObjectTypes()
{
    return new Dictionary<string, Type>
    {
        {"Class1", typeof(Class1)},
        {"Class2", typeof(Class2)}               
    };
}

But C# 6.0, has enhanced this feature by making the keys as indexers that brings more readability in the code.

Read the values from the Dictionary

Now we can read the values from the Dictionary in the same way as we are used to

 private static dynamic GetObject(string key)
{            
    return Activator.CreateInstance(ObjectTypes()[key]) as dynamic;
}

We are passing the "key" and getting the value from the Dictionary object and then creating the object instance at run time. Since we want to use the object methods/properties at run time, we are casting it into dynamic.

Client Invocation

Now let's invoke the dictionary as under

GetObject("Class1").ClassMethod();

The method "ClassMethod()" is invoked at run time. 

A complete implementation is as under

using System;
using System.Collections.Generic;

namespace ConsoleApplication2
{
    class Program
    {       
        static void Main(string[] args)
        {
             Console.WriteLine(GetObject("Class1").ClassMethod());
             Console.ReadKey();

        }

        private static dynamic GetObject(string key)
        {            
            return Activator.CreateInstance(ObjectTypes()[key]) as dynamic;
        }

        private static Dictionary<string, Type> ObjectTypes()
        {

            return new Dictionary<string, Type>
            {
                ["Class1"] = typeof(Class1),
                ["Class2"] = typeof(Class2)               
            };
        }
    }

    internal class Class1
    {
        public string ClassMethod()
        {
            return "From Class 1";
        }
    }
    internal class Class2
    {
        public string ClassMethod()
        {
            return "From Class 2";
        }
    }    
}

The result is From Class 1

Conclusion

In this article we have learnt about the Dictionary Initializer of C# 6.0. Hope this will be helpful. Thanks for reading.