Wednesday, February 10, 2016 [Tweets] [Favorites]

Dates, Done Right

Mark Bernstein:

But, back before they invented railroads, there were no time zones. And OS X knows this! So, before time zones were introduced, the local time doesn’t get shifted to the time zone. And, if your local time is one a different calendar date than Greenwich, you’re off by one day!

[…]

No one is going to anticipate bugs like this, bugs that depend on the invention of the railroad. TDD is great, but Coplien is right; you’re never going to get everything through testing.

Apple’s documentation policy attempts to tell you what you need to know, and no more. This gives Apple flexibility to improve OS X in small ways without breaking its implicit contract with developers, and keeps the documentation small. Here, though, the time zone behavior is completely undocumented.

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