using System;

public class Program

{

    public static void Main()

    {

        TestClass test = new TestClass();

        test = "alpha";     

        Console.WriteLine(test);

    }

}

​

public class TestClass

{

    public string something;

    public override string ToString()

    {

        return something;

    }

    public static implicit operator TestClass(string value)

    {

        var result = new TestClass();

        result.something = value;

        return result;

    }

}

​