Interface naming convention [closed]

Question

This is a subjective thing of course, but I don't see anything positive in prefixing interface names with an 'I'. To me, Thing is practically always more readable than IThing.

My question is, why does this convention exist then? Sure, it makes it easier to tell interfaces from other types. But wouldn't that argument extend to retaining the Hungarian notation, which is now widely censured?

What's your argument for that awkward 'I'? Or, more importantly, what could be Microsoft's?

Answer 1

I know the Microsoft guidelines recommends using the 'I' to describe it as an interface. But this comes from IBM naming conventions if I'm not remember wrong, the initiating 'I' for interfaces and the succeeding *Impl for the implementations.

However, in my opinion the Java Naming Conventions is a better choice than the IBM naming convention (and not only in Java, for C# as well and any OO programming language). Interfaces describes what an object can be able to do if it implements the interface and the description should be in verb form. I.e Runnable, Serializable, Invoiceable, etc. IMHO this is a perfect description of what the interface represents.

Answer 2

Thing is more readable name than IThing. I'm from the school of thought that we should program to interfaces rather than specific implementations. So generally speaking, interfaces should have priority over implementations. I prefer to give the more readable name to the interface rather than the implementation (i.e., my interfaces are named without the 'I' prefix).

Answer 3

I think it is better than adding a "Impl" suffix on your concrete class. It is a single letter, and this convention is well established. Of course you are free to use any naming you wish.