But what if the the classes are intentionally written and maintained with this in mind? Users don't even need to peek inside when the action is supported through methods. Maintaining sibling subclasses that rely on the same parent doesn't seem abusive or even unusual.

An example of my own use is dealing with user instances. Prior to validation, users interact with the system via an instance of the anon_user class. Should they log in, their instance is elevated into one of the user classes (depending on their status). The effects of some methods will change, and additional data might get grafted on. But I also want all the information I've already collected when I go to create their validated user object, and lo, there it is behind the anon_user veil, ready and waiting. Sometimes they go through a cascade of changes in user-type. What would be the object-appropriate way for me to go from one state to the next in such a situation?

I can agree with you that it doesn't make sense to grab a random data structure ("how it's implemented") and start abusing it. The author should have the freedom to make any changes they want under the hood. But when you are the author, such preservation and re-use of data structures seems prudent if applicable.

"One is enough. If you are acquainted with the principle, what do you care for the myriad instances and applications?"
- Henry David Thoreau, Walden

In reply to Re^4: Re-blessing || Re-constructing objects by blogical
in thread Re-blessing || Re-constructing objects by blogical

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