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copied!<p>It sounds like you're asking whether there's a "concretely useful" benefit to using the state design pattern, to which I'd say definitely yes, particularly if your app actually relies heavily on the "state" of its objects. A popular canonical example is that of the video player, which is always in one state, and can only transition into different states depending on the state it's currently in (e.g., it can't stop if it's already stopped, but it can play, and it can rewind, and so on). </p> <p>While that particular example can be managed relatively easily with a handful of if/else/switch-type conditions (if (isStopped()), play(), etc.) because there aren't that many states to deal with, when states or their transition rules start to become more numerous or complicated, the state pattern absolutely becomes quite valuable, as without it, your code tends to accumulate elseifs like crazy, and things become less and less readable and manageable over time.</p> <p>So yes, in general, if you find your objects' behaviors varying according to their states (if isStopped() play() / elseif isPlaying() stop() / elseif (isBroken() fix()), etc.), then yes, do consider using the State pattern. It's a bit more work up front, but generally well worth the effort, and done right I doubt you'd notice any significant overhead simply for the using of it.</p> <p><a href="http://rads.stackoverflow.com/amzn/click/0596007124" rel="nofollow noreferrer">Head First Design Patterns</a> offers a great description of its hows and whys, too -- I highly recommend picking up that book to pretty much anyone writing object-oriented code.</p>

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