Comment by mbell | Hacker News Reader

Comment by mbell | Hacker News Reader

Parent Full thread

> Getters and setters, C# style. That is, instead of

I just stopped using getters and setters all together unless I have a real use for them. The most common reasons are: because they are required by some third party library or they are the external interface for whatever the module of code is doing. For all internal classes, if the field needs external access, just make it public.

Most of the arguments I hear for using getters and setters are the result of the tendency in the Java world to over engineer everything. e.g. "What if you want to change the internal name in 8 months? or add validation years from now? or add some logic to the getter? (ignoring the fact that would no longer make it much of a 'getter')"

The only argument that holds water with me for using getters/setters everywhere, because it is actually painful, is mocking field values, but there are ways around that and the trade off in code readability with public fields is well worth it.

I really disagree that C# getters and setters are less readable than a public field. Compare:

   public string Field { get; set;}

to

   public string field;

I felt I had to reply to this comment to discourage this practice for a couple of reasons:

1) By convention anyone reading your code will think this is very strange, and it will force them to spend additional time reading your code to understand why you are breaking such a strong convention.

2) Using properties really will make your life easier when you need to track down a state change in your program. Detecting a state change on a public setter is a lot easier than detecting state change on a public field.

3) In C#, at least, using public fields where you should be using public properties will make creating an interface on existing code significantly more difficult - as interfaces can only define public properties, and not fields.

In short please don't do this. It's really bad practice just to save a couple extra characters, and if I inherit your code someday I'll probably want to strangle you.

1 + 2 are exactly why I do it. If your muddling around with the internal state of another object there should be alarm bells in your brain triggering you to think "should i really be doing this?"; It should look weird.

Hiding fields behind method calls obscures what your really doing. I like that syntax highlighting changing the color on field access and that there aren't parenthesis at the end of the call. This is what I meant by readability, I instantly know that I'm muddling around with the inner state of another object. Figuring out whats really going on with getter and setters is made far worse by the common practice of 'overloading' getters and setters to accept / return different types than the internal state representation.

3 - I would consider defining field getters in an interface poor form. There is a reason interfaces (in Java at least) do not allow field definitions. Defining a 'getter' in an interface is just circumventing that protection and a strong indication the code should be refactored in a different way.

In C#, properties are handled just like fields:

    class Foo {
       public string Bar { get; set; }
    }

    Foo.Bar = "test";

But I still don't get why wouldn't you use getters/setters or properties. For example, let's say you want to get the number of items in a list. How'd you do it without something like this

    public int Count { get; private set; }

?

Things consuming an object shouldn't care how it does what it asks, only that the object does it.

If knowing that something is a field rather than an opaque getter is important to the consumer, then the consumer knows too much.

You know you're messing with the state of an object when you do object.Something. That it's being messed with by a method call or a field is immaterial.

The syntax for consuming a field or a property are exactly the same. I don't see how fields ring alarm bells while properties don't.

I think it's partly a defensive tactic to stop others playing fast and loose with your object state.

I used to write classes and then add fields and auto generate getters/setters.

Now I don't, I just make all the state private and if I find myself wanting a getter/setter I ask myself why.

Too much use of getters/setters is just reinventing the problem that private state was meant to avoid.

So for example rather than:

if(email.getState() == EmailState.SENT) {

I have:

if(email.wasItSent()) {

What if a 3rd-party API only works on Beans? (i.e. doesn't support private properties).

With dependency injection frameworks, you don't really need setters anyway. I add getters only as needed, unless it's a public API.

2 things: 3rd-party API that only works on "beans" and thin object (not your Services or DAOs that use DI heavily).

You can't do much with 3rd-party APIs. For thin objects, a best practice is to keep them immutable by having only getters, but then you generally end up with Builder boilerplate.

Reply on news.ycombinator.com