Question

I often find I want to write code something like this in C#, but I am uncomfortable with the identifier names:

public class Car {     private Engine engine;     public Engine Engine     {         get         {             return engine;         }         set         {             engine = value;         }     }     public Car(Engine engine)     {         this.engine = engine;     } } 

Here we have four different things called ‘engine’:

• Engine the class. Engine seems like a good, natural name.
• Engine the public property. Seems silly to call it MyEngine or TheCarsEngine.
• engine the private field backing the property. Some naming schemes will recommend m_engine or _engine, but others say that all prefixes should be avoided.
• engine the parameter name on the constructor. I’ve seen naming schemes that recommend prefixing an underscore on all parameters, e.g., _engine. I really dislike this, since the parameter is visible to callers via Intellisense.

The particular things I don’t like about the code as written are that:

• If you change the parameter name in the constructor but miss a use of it in the constructor body, you get a subtle bug that the compiler probably won’t be able to spot.
• Intellisense has a bad habit of autocompleting the wrong thing for you, and sometimes you won’t notice it’s changed the case. You will again get a subtle bug if the constructor body accidentally ends up this.engine = Engine;

It seems that each name is appropriate in isolation, but together they are bad. Something has to yield, but what? I prefer to change the private field, since it’s not visible to users, so I’ll usually end up with m_engine, which solves some problems, but introduces a prefix and doesn’t stop Intellisense from changing engine to Engine.

How would you rename these four items? Why?

(Note: I realise the property in this example could be an automatic property. I just didn’t want to make the example overcomplicated.)

See also: Am I immoral for using a variable name that differs from its type only by case?

Answer 1

In this case, I would name them exactly as they are in the example.

This is because the naming is clear as to what data each element holds and/or will be used for.

The only thing I would change for C#3 is to use an auto-property which would remove the local variable.