有没有更简洁的方法来结合Ruby中的许多比较？

Question

I currently have this if statement:

if Time.now.day == 1 and Time.now.hour == 0 and Time.now.minute == 0 and Time.now.second == 0

Is there a more concise way to do this?

Answer 1

You can use Time#to_a to convert your time to an array (sec, min, hour, day, month, year, wday, yday, isdst, zone):

Time.now.to_a  # => [20, 57, 16, 30, 11, 2010, 2, 334, false, "CET"]

then slice off just the part you want to match against:

Time.now.to_a[0,4]  # => [20, 57, 16, 30]

Your particular check can then be made as concise as this:

if Time.now.to_a[0,4] == [0,0,0,1]

Answer 2

[:day,:hour,:minute,:second].map{|s|Time.now.send s}==[1,0,0,0]

Answer 3

The standard Ruby Time library is pretty spare, so I would simply add my own method to make this easier:

class Time
  def beginning_of_month
    Time.local(self.year, self.month, 1)
  end

  def beginning_of_month?
    self == beginning_of_month
  end
end

so you could then write:

if Time.now.beginning_of_month?

Answer 4

How about?

Time.now.strftime('%d %H:%M:%S') == '01 00:00:00'

I like this because it's very self-documenting; It's obvious you're comparing to a certain day at midnight.

Explanation: The strftime() method makes it easy to output a custom date and/or time string. This format is outputting the day of the month, hour, minute and second.

Time.now.strftime('%d %H:%M:%S') #=> "01 16:54:24"

Answer 5

You can compare it to a time you created:

if Time.now == Time.at(0)

or

if Time.now == Time.utc(2000,"jan",1,20,15,1)

Answer 6

I guess that you are trying to make something similar to cron , ie you are in an endless loop and checking whether time has come to perform certain action.

If that is the case, I don't think you should rely that your timestamp check will fall exactly on the first second of the day. What would happen if is delayed (for any reason), and first it fires on 23:59:59 , and the next cycle happens on 00:00:01 instead of :00 ? You will fail to perform desired action whatsoever.

Also, you would want to include some sleep , so that your empty loop wouldn't consume all you resources while waiting.

What you could do instead, is keep the last action timestamp, and compare now with the next action timestamp, performing the action if now >= next_timestamp . Something like:

last_action_on = Time.at(0)
loop do
  now = Time.now
  next_action_on = Time.local(now.year, now.month, 1) # beginning of the current day
  if last_action_on < next_action_on && now >= next_action_on
    last_action_on = now
    do_action
  end
  sleep 1
end

Answer 7

 %w(day==1 hour==0 minute==0 second==0).all? { |e| eval "Time.now.#{e}" }