ruby 中的时间操作 [英] Time manipulation in ruby

问题描述

我想创建一个位于未来 20 分 10 秒的 DateTime 实例.我在 irb 中尝试使用 Time 和 DateTime，但似乎无法找到真正有意义的方法.我只能向 DateTime 对象添加天数，而只能向 Time 对象添加秒数.

I want to create a DateTime instance that lies 20 minutes and 10 seconds in the future. I tried around with Time and DateTime in irb, but can't seem to figure out a way that really makes sense. I can only add days to DateTime objects and only add seconds to the Time objects.

没有比总是将我想要添加的时间转换为秒更好的方法了吗?

Isn't there a better way than to always convert the time I want to add into seconds?

推荐答案

A Time 是自一个纪元以来的秒数，而 DateTime 是自纪元以来的天数一个时代，这就是为什么将 1 添加到 DateTime 会增加一整天.但是，您可以添加一天的分数，例如

A Time is a number of seconds since an epoch whereas a DateTime is a number of days since an epoch which is why adding 1 to a DateTime adds a whole day. You can however add fractions of a day, for example

d = DateTime.now
d + Rational(10, 86400)

将为 d 添加 10 秒(因为一天有 86400 秒).

Will add 10 seconds to d (since there are 86400 seconds in a day).

如果您使用的是 Rails，Active Support 会添加一些辅助方法，您可以这样做

If you are using Rails, Active Support adds some helper methods and you can do

d + 20.minutes + 10.seconds

正确的做法是 d 是 DateTime 或 Time.您可以单独使用 Active Support，现在您可以只获取您需要的部分.我似乎记得这个东西在 activesupport/duration 中.我相信还有其他一些宝石也可以帮助处理时间.

Which will do the right thing is d is a DateTime or a Time. You can use Active Support on its own, and these days you can pull in just the bits you need. I seem to recall that this stuff is in activesupport/duration. I believe there are a few other gems that offer help with time handling too.

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