I’m using a LiveWriter plugin — unfortunately, I can’t seem to find the name of it.

I can tweak the formatting, so I’ll give that a look.

Nick

This is just typical information hiding — the actual declaration of the class doesn’t matter and thus isn’t made public. The property exposes the functionality.

You can, of course, design things totally differently if you like.

Nick

I copied the code right out of the Code Editor and pasted it into a formatting tool. That may have done something to the font.

Nick

Marshall cites an enumerator as a good candidate for a nested class, but it shouldn’t be a _private_ nested class. It should be public. That lets consumers of the class enumerate its contents. Maybe the "for-in" loop can use a private nested class, but the rest of us can’t, and not all enumerations fit the "for-in" model.

And Nick, your code isn’t valid. It’s using left single quotation marks instead of apostrophes. Delphi doesn’t support curly quotes, does it?

Probably the best example is a collection with a specific collection type. The specific type is meaningless outside the context of the collection itself, so it makes sense to nest it within the collection itself.

Nick

this highlights one of the disadvantages of having to fully declare classes in the interface section of a unit: Since the nested class is private, there is no need for it to be part of a unit’s interface section, it only confuses programmers who use the class.
This would be much tidier if it were possible to declare anything that’s private in the implementation section only. IIRC there is at least one QC report on this issue.

twm

Besides keeping the namespace a little tidier, it allows you to restrict access to classes that you are forced to declare publicly (such as enumerators).