All code has a cost, primitives have a lower base cost because they are universal in the language and thus every programmer will automatically know how to use them. Before introducing a custom object with yet another API to be learned, you need justification.
> Implement Money class if you need to deal with money, it’s much better than using floats all over the place. Don’t use Hash for configuration objects, use a custom Configuration class instead.
Let's pretend he said integer since floats for money is outright broken. Yes, Money is a clearcut case where having a money-specific API is both intuitive and immediately useful.
Configuration on the other hand is debatable. If you're just doing things a hash does then it's fine. If you find yourself with lots of helper methods or repeating the same transformations over and over then that's when you have a code smell that may warrant lifting configuration to its own level.
But the critical thing is to remember that there's a non-trivial cost to creating domain-specific objects.
Oh, and might I suggest that you consider doing it in pennies rather than fractional dollars? It will work out better.
Better to understand the underlying territory, I think. That would not be over-engineering.
Also, regarding DSLs, there is a tradeoff there that's worth commenting as well. A DSL pays the most dividends when the domain is understood (such as HTTP in the case of Sinatra), but if it's custom business logic than there may not be enough common business understanding for a DSL to be intuitive, and in that case it's just another layer of indirection to follow through as you inspect the code to figure out what it's actually doing. Half-baked DSLs are harmful IMO.
This reminds me of a story I read on Reddit that someone told about his dog. The first time his dog saw a horse, the dog was excited, and ran up to sniff the horse through the fence.
It was an electric fence, and the dog touched it with his nose. The dog found this extremely unpleasant.
Now the dog is deathly afraid of horses, and runs and hides whenever he sees a horse.
Personally I'm on the fence but when you look at how much boilerplate this Virtus example needs to get rid of the code "smell" you have to wonder if maybe he has a point.
And funnily enough I had the itch to say I'm a primitive obsessive today: http://williamedwardscoder.tumblr.com/post/25916255470/taxon...
It almost feels like a reply to this post, but it was an coincidental bit of pontification.
In OO code I try to create types to represent every concept in my code. It seems overkill at first but I have found in most cases it pays off with reduced duplication. It almost always removes the question of where to put static utilities. Lets say you have a postcode - by creating a Postcode type you can put postcode validation, postcode formatting, etc, directly on that type rather than floating in different parts of your codebase.
Additionally, in a statically typed language it adds type safety - so for example you can't pass a postcode into an address parameter.
If you return a Hash of attributes everyone knows how a Hash works, but if you return a custom Attributes object people have to learn how it works, there could be bugs, etc.
oh and since it's an enumerable it's easy to work with it just like with a hash.
I'm also not saying you should never ever use primitive objects because that would be silly :) The trick is to determine when it is better to use a custom class instead of misusing existing primitive ones. Hash is a good example in Ruby, people use it way too often.
Although I also wouldn't say that it simplifies your code... What it does is make the api to that class/object more explicit. At the very least you are keeping the complexity level the same, but you might also be making it more complicated. If you're just talking about the idea of OO encapsulation in general, that's another thing.... Not that I disagree that an explicit api is a good thing.
"The simple structure and natural applicability of lists are reflected in functions that are amazingly nonidiosyncratic. In Pascal the plethora of declarable data structures induces a specialization within functions that inhibits and penalizes casual cooperation. It is better to have 100 functions operate on one data structure than to have 10 functions operate on 10 data structures."
So, IMO it depends on the language features available and the scenario whether it is a code smell. For instance, Haskell allows you to introduce a new type whose data representation is the same as the original type using newtype [1]. In contrast to a type alias, newtype makes a different type, but it still allows you to define functions on that type in terms of the original type (using the type's constructor). If you want to hide the underlying representation, you simply do not export the constructors from the enclosing module.
tl;dr: in Haskell you do get a better abstraction without the overhead. I am pretty sure many other language can do as well (private inheritance in C++?).
[1] http://www.haskell.org/onlinereport/decls.html#datatype-rena...
