using System;

using System.Text;

// see: https://stackoverflow.com/a/58200607/1016343

public class Program

{

    public static void Main()

    {

    var log = (StrBuilder)"Hello "; // same as: "Hello ".ToStrBuilder();

    log += "World!";

    log += "\n This example shows how to extend StringBuilder";

    log.ToString().Dump();

    }

}

​

public static class Extensions

{

    public static StrBuilder ToStrBuilder(this string str)

    {

        return new StrBuilder(str);

    }   

}

​

public class StrBuilder

{

    private StringBuilder sb;

​

    public StrBuilder()

    {

        sb = new StringBuilder();

    }

​

    public StrBuilder(string strB)

    {

        sb = new StringBuilder(strB);

    }

​

    public static StrBuilder operator +(StrBuilder sbA, string strB)

    {       

        return sbA.Append(strB);

    }

    public static implicit operator StrBuilder(string self)

    {

        return new StrBuilder(self);

    }

​

    public StrBuilder Append(string strB)

    {

        sb.Append(strB);

        return this;

    }

​

    public override string ToString()

    {

        return sb.ToString();

    }

}

​