exception handling - Putting out fires gets old - Custom exceptions

Head First C#:
A Learner's Guide to Real-World Programming
with C# and .NET
Kindle版

開発環境

Head First C Sharp: A Learner’s Guide to Real-World Programming with C Sharp and .NET (Andrew Stellman(著)、Jennifer Greene(著)、O’Reilly Media)の Chapter 12(exception handling - Putting out fires gets old)、p.643(Exception Magnets)の解答を求めてみる。

コード

Program.cs

using ConsoleApp1;

Console.Write("when it ");
ExTestDrive.Zero("yes");
Console.Write(" it ");
ExTestDrive.Zero("no");
Console.WriteLine(".");

MyException.cs

namespace ConsoleApp1;

public class MyException : Exception { }

ExTestDrive.cs

namespace ConsoleApp1;

public class ExTestDrive
{
    public static void Zero(string test)
    {
        Console.Write("t");
        try
        {
            DoRisky(test);
            Console.Write("o");
        }
        catch (MyException)
        {
            Console.Write("a");
        }
        finally
        {
            Console.Write("w");
            Console.Write("s");
        }
    }
    static void DoRisky(string t)
    {
        Console.Write("h");
        if (t == "yes")
        {
            throw new MyException();
        }
        Console.Write("r");
    }
}

入出力結果(Terminal, Zsh)

% dotnet run
when it thaws it throws.
%