Get Rid of That Code Smell – Primitive Obsession
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Re: Get Rid of That Code Smell – Primitive Obsession
#2Do not hastily judge sticking to primitives as bad. Here's a relevant SICP quote:
"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."
Re: Get Rid of That Code Smell – Primitive Obsession
#3It's an interesting article, but I'm not really sure this is the best approach. In terms of having the 'best' code that is 100% OO then sure, but in terms of actually having usable, understandable, code I'm not sure I agree.
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.
Re: Get Rid of That Code Smell – Primitive Obsession
#4It's an interesting article, but I'm not really sure this is the best approach. In terms of having the 'best' code that is 100% OO then sure, but in terms of actually having usable, understandable, code I'm not sure I agree. 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.
We needed a set-like data structure with enumerable interface that would also know how to handle attributes from parent classes. That's why a custom object worked better.
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.
Re: Get Rid of That Code Smell – Primitive Obsession
#5It's an interesting article, but I'm not really sure this is the best approach. In terms of having the 'best' code that is 100% OO then sure, but in terms of actually having usable, understandable, code I'm not sure I agree. 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.
reminds me of json builder in ruby, yikes!
Re: Get Rid of That Code Smell – Primitive Obsession
#6The potential danger in computationally intensive code is that you have a number of wrappers around the actual data (e.g. in the article AttributeSet wraps a hash table), each requiring a pointer dereference and a vtable lookup.
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...
Re: Get Rid of That Code Smell – Primitive Obsession
#7There's another code smell that every programming whiz kid produces at some point: over-engineered.
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.
Re: Get Rid of That Code Smell – Primitive Obsession
#8There's another code smell that every programming whiz kid produces at some point: over-engineered. 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…
The justification is simple, to allow for testing concerns the code uses. I see domain specific objects the same way I see domain specific languages - if I cannot grasp it by looking at it then it's broken, meaning I should not have to read documentation but simply understand the domain the object / language represents e.g sinatra get()... etc.
Re: Get Rid of That Code Smell – Primitive Obsession
#9This is exactly the opposite of the advice recently given by Rich Hickey in his keynote at RailsConf 2012, where he strongly recommends using simple, transparent data structures without a lot of OO wrapping baggage.
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.
Re: Get Rid of That Code Smell – Primitive Obsession
#10There's another code smell that every programming whiz kid produces at some point: over-engineered. 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…
> Let's pretend he said integer since floats for money is outright broken.
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.