Composing the Parts Object

By definition a parts list contains a list of individual parts. It’s time to add a class to represent a single part. The class name for an individual part clearly ought to be Part but introducing a Part class when you already have a Parts class makes conversation a challenge. It is confusing to use the word “parts” to refer to a collection of Part objects, when that same word already refers to a single Parts object. However, the previous phrase illustrates a technique that side steps the communication problem; when discussing Part and Parts, you can follow the class name with the word “object” and pluralize “object” as necessary.

You can also avoid the communication problem from the beginning by choosing different class names, but other names might not be as expressive and may well introduce communication problems of their own. This Parts/Part situation is common enough that it’s worth dealing with head-on. Choosing these class names requires a precision of communication that’s a worthy goal in itself.