Wednesday, February 10, 2016

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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