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Real world objects don't have this property? Some do. When the gear shift lever on my Mazda is in one of the automatic slots, you can't upshift or downshift ma
by raganwald 17y ago
Real world objects don't have this property?
Some do. When the gear shift lever on my Mazda is in one of the automatic slots, you can't upshift or downshift manually.
In business this is even more obvious. Contracts might have states: proposed, drafted, agreed, signed, and so forth. You can't sign a draft, it has no meaning. That's part of the business process.
- wwalker3 17y agoNot quite the same. Your Mazda shift lever's manual slot doesn't disappear when you're in automatic. You can still sign a draft contract, it's just not binding. In the software case you explained, the interface changes so you can't even try to do the wrong thing. On real-world objects, you can always try to do the wrong thing, it just doesn't work.
- raganwald 17y agoYou cannot sign a draft, signing is a legal thing, not just a putting your name on a piece of paper thing. Imagine you're a manager and you call your EA: "Henderson, get me the YC contract to sign!" Henderson replies back on the squack box: "Sorry sir, it's still a draft, it has to be approved by legal before you can sign it." > Your Mazda shift lever's manual slot doesn't disappear when you're in automatic No it doesn't, but you can't actually move the lever there without changing the gearbox's state from Drive to Manual. So, we can say that it has an interface including the messages "+" and "-" at all times (The slot), but there's no way to send it a "+" or a "-" message unless the gearbox state is "M."