From: Sam Roberts <sroberts@...>
Date: 2004-04-01T10:02:11+09:00
Subject: Re: Representing Time Ranges (Difference)

Quoteing cc1@cec.wustl.edu, on Thu, Apr 01, 2004 at 07:44:25AM +0900:
> Hmm, perhaps I scanned it too quickly, but this feels more like a 
> library to manipulate date ranges, as opposed to formatting a time span. 
>  Basically I want to be able to represent time spans in a more 
> meaningful manner then individual seconds.  I know all I need to do is 
> do a bunch of divide / modulus operations to find this out, but I was 
> wondering if there was a prewritten module to nicely format time spans 
> and allow easy access to the number of months, days, hours, seconds in 
> between to time or date objects.

Well, I've been meaning to do this, for the same reasons (I have
durations in seconds, and I want to print them in more human units).

I hacked this up. It works OK, but only up to days.

I could extend it to years, but it turns out months is hard to do. Given
a span in seconds, you don't know how many months that is, unless you
know the date at one end of the span.

So, maybe it would be possible to add a Duration.difference(t0, t1),
where t0 and t1 are either Time, Date, or DateTime, and then it would
be possible to break down the duration into years, months, days, ...

But, this hack will do me for now. If you get something better going,
pls share it around!

Cheers,
Sam


=begin
  $Id: duration.rb,v 1.1 2004/04/01 01:00:29 sam Exp $

  Copyright (C) 2004 Sam Roberts

  This library is free software; you can redistribute it and/or modify it
  under the same terms as the ruby language itself, see the file COPYING for
  details.
=end

module Vpim
  class Duration
    SECS_HOUR = 60 * 60
    SECS_DAY  = 24 * SECS_HOUR
    MINS_HOUR = 60

    def initialize(secs)
      @secs = secs
    end

    def Duration.secs(secs)
      Duration.new(secs)
    end

    def Duration.mins(mins)
      Duration.new(mins * 60)
    end

    def Duration.hours(hours)
      Duration.new(hours * SECS_HOUR)
    end

    def Duration.days(days)
      Duration.new(days * SECS_DAY)
    end

    def secs
      @secs
    end

    def mins
      (@secs/60).to_i
    end

    def hours
      (@secs/SECS_HOUR).to_i
    end

    def days
      (@secs/SECS_DAY).to_i
    end

    def weeks
      (days/7).to_i
    end

    def by_hours
      [ hours, mins % MINS_HOUR, secs % 60]
    end

    def by_days
      [ days, hours % 24, mins % MINS_HOUR, secs % 60]
    end

    def to_a
      by_days
    end

    def to_s
      Duration.as_str(self.to_a)
    end

    def Duration.as_str(arr)
        s = ""
      case arr.length
        when 4
          if arr[0] > 0
            s << "#{arr[0]} days"
          end
          if arr[1] > 0
            if s.length > 0
              s << ', '
            end
            s << "#{arr[1]} hours"
          end
          if arr[2] > 0
            if s.length > 0
              s << ', '
            end
            s << "#{arr[2]} mins"
          end
          if arr[3] > 0
            if s.length > 0
              s << ', '
            end
            s << "#{arr[3]} secs"
          end
        when 3
          if arr[0] > 0
            s << "#{arr[0]} hours"
          end
          if arr[1] > 0
            if s.length > 0
              s << ', '
            end
            s << "#{arr[1]} mins"
          end
          if arr[2] > 0
            if s.length > 0
              s << ', '
            end
            s << "#{arr[2]} secs"
          end
      end

      s
    end
  end
end