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i4☕

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Code that smells aka ‘bydlo-code’

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kill me, please

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don’t write code that smells

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there was a dev team…

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there was a dev team… …writing on ObjC

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and they decided to switch to Swift!

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and they decided to switch to Swift! in production!

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it was nice morning and PM decided to install app

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it was nice morning and PM decided to install app on device!

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it’s not us! it’s new 7.3 Xcode!

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oh no, it’s us :(

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"loadData has not been implemented" found in logs

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– loadData(…) -> … – loadData(…) -> … ChildTableViewController BaseTableViewController

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BaseTableViewController – loadData(…) -> … ChildTableViewController – loadData(…) -> … generics stub overriden

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BaseTableViewController – loadData(…) -> … ChildTableViewController – loadData(…) -> … generics stub overriden not called at all

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A – architecture

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Problem solving

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What if we disable optimization?

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let’s disable optimization..

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too many optimizations! swift compiler optimization!

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Why debug is ok?

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…Testability

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Debug Release Optimization Testability WMO yes WMO no

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WMO https://developer.apple.com/swift/blog/?id=27 if method has no ‘internal’ access, compiler may mark it as ‘final’

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Testability allows you to use all ‘internal’ methods in tests like ‘public’

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everything is ok overriden methods may be lost Debug Release Optimization Testability WMO yes WMO no

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tweet all the things!

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tweet all the things!

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sudden help!

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sudden help! swift contributor

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https://gist.github.com/PaulTaykalo/5c97010874a93626ca3c Minimal crashable code

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http://openradar.appspot.com/radar?id=4971716266688512 Filed Radar

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SIL devirtualization: Conservatively avoid filtering devirt candidates on generic base classes Fix by @jckarter https://github.com/apple/swift/pull/1954

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SIL devirtualization: Conservatively avoid filtering devirt candidates on generic base classes Fix by @jckarter https://github.com/apple/swift/pull/1954

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Fix by @jckarter fix! https://github.com/apple/swift/pull/1954

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Tests https://github.com/apple/swift/pull/1954

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Swift 2.2 Patch https://github.com/apple/swift/pull/1954

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Lessons learnt

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Lesson #1 every decision has consequences

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sooner or later they’ll appear Lesson #1 every decision has consequences

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Lesson #2 always try build in release on device

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at least once a day Lesson #2 always try build in release on device

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and community Lesson #3 twitter rulez

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Lesson #4 PMs are useful

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sometimes Lesson #4 PMs are useful

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team: Vitaliy, Igor, Paul Thanks community: @akosma, @jckarter PM: Anna

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