Fix: TimeWithzone bug #40448
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Fix: TimeWithzone bug #40448
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Why this commit? TimeWithZone instances were unexpectedly being rounded up. What changes were made and why? Internally, .to_f was being called on TimeWithZone instances. This can lead to inaccuracies if Rationals are involved. Using .to_r instead of .to_f will be more accurate, but it does come with a slight computational cost.
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eugeneius
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Oct 25, 2020
| @@ -47,7 +47,9 @@ def at_with_coercion(*args) | |||
| # Time.at can be called with a time or numerical value | |||
| time_or_number = args.first | |||
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| if time_or_number.is_a?(ActiveSupport::TimeWithZone) || time_or_number.is_a?(DateTime) | |||
| if time_or_number.is_a?(ActiveSupport::TimeWithZone) | |||
| at_without_coercion(time_or_number.to_r).getlocal | |||
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I went ahead with this to ensure that #40413 is fixed in the next release. Thanks! |
This was referenced Oct 30, 2020
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eugeneius
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Oct 30, 2020
Fix: timezone bug - rounding problem
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Summary
What was the problem?
There was a rounding off issue here when we were comparing TimeWithZone times with DateTime raised in #40413. I have written a failing test and made it pass.
How did we fix it?
The problem was that when we using time_instance.to_f - this was not accurate enough in certain cases. I have attempted to solve it by ensuring that we use Rationals when creating Time instances time_instance.to_r . (there is a slight performance cost to this, but the benefit is accuracy).
Thanks for reviewing and I hope this helps.
rgds,
Ben