Re^3: The Accessor Heresy

The point I'm trying to make is that certain properties are derived from others, and while you can go in both directions, there's often a good point not to do so. I agree that there are without any doubt some circumstances in which you'd determine the radius from the area, but this is irrelevant to the discussion.

My point is that getters and setters very often don't come in pairs.

I hope this clarifies things a bit, -gjb-

Comment on Re^3: The Accessor Heresy

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Re^4: The Accessor Heresy by sauoq (Abbot) on Nov 28, 2005 at 17:40 UTC
My point is that getters and setters very often don't come in pairs. Okay, you have clarified your point successfully. I don't really agree with this either, though. It all depends on what you have to do with your objects. Having two or more inter-related properties, any of which can be set and thereby affect the others, is not particularly rare. Running with the original example, if you sold custom made hand-woven circular rugs and charged by the square foot, you might be able to imagine situations in which setting either the area or the radius might be important. -sauoq "My two cents aren't worth a dime.";	[reply]
Re^4: The Accessor Heresy by Roy Johnson (Monsignor) on Nov 28, 2005 at 18:36 UTC
getters and setters very often don't come in pairs To help in applying what you've read here to situations that aren't specifically covered, think about whether something is conceptually a property. If you've got a bunch of operate_on_`Doohickey` type methods, regardless of whether any of them happen to be `get_` or `set_`, you probably have in your model the concept of a Doohickey property. If you've got only one operate_on_`Doohickey` method, there's still probably a Doohickey object in your model, but it's not interesting enough to implement as an object. Of course, you might expand your functionality in the future, in which case you might end up wishing you had coded it up as an object. I definitely wouldn't code up an object for a read-only property. If `Area` wasn't settable, then my Circle object might have an `Area` method that simply returned the area of the Circle. Note that it wouldn't be `getArea`. But if it had numerous possible output formats, I'd have it create a Measurement object (not a sub-object, but one that exists outside of the Circle class hierarchy, because it's not specific to the domain of Circles) so I could get `Area->inSqFeet` or whatever. The design decisions are yours, of course. Caution: Contents may have been coded under pressure.	[reply] [d/l] [select]
Re^5: The Accessor Heresy by gjb (Vicar) on Nov 28, 2005 at 19:03 UTC
Hm, I'm a bit suspicious about the manipulating the "inner" Doohickey object, but it's hard to tell without the specifics. If it were my code I'd start analyzing dependencies and refactoring, but then again, it's hard to tell without code. To me, it smells of an object model which is not quite aligned with what it is trying to model. As ever, just my 2 cents, -gjb-	[reply]


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