Andy Matuschak on Twitter: "♲ “Mutability, aliasing, and the caches you didn’t know you had”: http://t.co/bHTQGTZzLH New post on Garbage Collective." / Twitter

♲ “Mutability, aliasing, and the caches you didn’t know you had”: garbagecollective.quora.com/Mutability-ali New post on Garbage Collective.

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Mutability, aliasing, and the caches you didn't know you had

Many engineers have developed an intuition that mutable state is dangerous and can make programs harder to maintain. Still, it's worth digging into the specifics of why mutability is dangerous so we...

4:05 PM · Jul 9, 2013Tweetbot for Mac

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@pbowden

@cbarrett

Thanks, Phillip. Still don’t know the right place to put the boundary between logic + imperative…

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Very nice! I hadn't thought about it in terms of cache invalidation before but that's a great view on it.

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Yup. Implicitly caching of UI state is the devil. Hard to get right without being bitten by doing it wrong.

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Imagine if methods called via a timer couldn't set ivars/properties/global state and were forced to only read existing data!

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on a past Java project, all derived data was dependent on values directly from the UI. It was very hard to read.

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it was mostly just an experiment to see what that would look like on a real project.

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I made the same argument about caching you make here to convince others that it was worth doing. :)

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