Today I was introduced to a new kata - The Expense Report! https://github.com/christianhujer/expensereport Being in the corporate world, sounds like a good kata to give a go. I'll be doing it in C#, shocker, I know. The process of the kata is laid out as follow…
Still Green; Keep Refactoring Let's take another look at Money; there's eight methods. Five of these methods delegate the work to another object, "I know what I want, you know how to do it". The remaining three don't. To make "Similar things more similar" we have to consider refactoring these…
GET TO THE PRIMITIVE While we very much want to avoid data flowing through our system, sometimes we need them. Sometimes we have to get back to a primitive type. This happens at the boundaries of our system. When our code passes to some other code, we probably have to…
No Primitives - Again Since we're poking around the ExchangeRates area, one thing has stood out to me. public interface IExchangeRateTo { double To(Currency currency); } This interface has a method that returns a double... a Primitive. That's ... Nooooooo! What can we do to fix this? Clearly a type of somekind.…
BONUS TECHNIQUES Let's look at some bonus techniques I use when working in projects. * PrivateCtor - Utility class to access private constructors * No Primitives - Exchange Rate returns a double * MicroObjects - We haven't hit the size limit yet; let's explore that. * ToSystemType - Not mentioned during this, but a…
No Primitives I'm VERY against primitives' being passed around in a system. As soon as I started putting in hard coded strings of the currency I knew it'd have to be extracted out into something that's not a primitive. I didn't do this earlier because it wasn't being asked for…
I'm Not Adding As mentioned, What about converting between currencies without adding currencies together? That seems like it'll be a useful thing for our system. Let's mark that as our current work in progress! > 5 USD * 2 = 10 USD 10 EUR * 2 = 20 EUR 4002 KRW / 4 = 1000.5 KRW…
Cross Equality The requirement we want to get to now is to allow our equality to work across currencies > 5 USD * 2 = 10 USD 10 EUR * 2 = 20 EUR 4002 KRW / 4 = 1000.5 KRW 5 USD + 10 USD = 15 USD 5 USD + 10 EUR = 17 USD 12 USD == 10…