From: "Ara.T.Howard" <ahoward@...>
Date: 2003-11-27T09:22:12+09:00
Subject: Re: Time#succ ?

On Thu, 27 Nov 2003, Paul Brannan wrote:

> Date: Thu, 27 Nov 2003 06:29:10 +0900
> From: Paul Brannan <pbrannan@atdesk.com>
> Newsgroups: comp.lang.ruby
> Subject: Re: Time#succ ?
> 
> On Mon, Nov 24, 2003 at 05:36:49AM +0900, Hal Fulton wrote:
> > Should this be added? It would enable the creation
> > of Time ranges like t1..t2 and so on.
> 
> Does this not already work?
> 
> [pbrannan@zaphod ruby]$ irb
> irb(main):001:0> t = Time.now
> => Wed Nov 26 16:27:46 EST 2003
> irb(main):002:0> (t .. t+1)
> => Wed Nov 26 16:27:46 EST 2003..Wed Nov 26 16:27:47 EST 2003
> 
> (the problem only comes if you want to iterate over the range, which
> seems to me to be an ill-defined operation).


anyone familiar with the 'jot' unix program?  i think ranges should work like
that - eg. one should be able to define the increment

day = 60 * 60 * 24

a = Time.now
b = Time.now + (7 * day) 

week = (a...b)

week.each(step = day) do |weekday|
  ...
end

as it is needs to overide the #succ method of an object for that to occur.


i realize this is problematic since currently ranges only rely on having a
#succ method, but perhaps this could be extend such that Range#each takes an
optional argument, step.  if this is given it will be passed to the objects
#step method, something similar to:


~ > cat timestep.rb

  class Range
    alias __each each
    def each step = nil, &block
      nxt, e = self.begin, self.end

      if nxt.respond_to? :step
        loop do
          yield nxt
          nxt = nxt.step step
          break if (exclude_end? ? nxt >= e : nxt > e)
        end
      else
        __each &block
      end
    end
  end

  class Time;
    def step n; self + n; end
  end

  a = Time.now
  b = Time.now + (7 * 24 * 60 * 60)

  week = (a...b)

  week.each(24 * 60 * 60) do |day|
    p day
  end

~ > ruby timestep.rb

Wed Nov 26 15:29:18 MST 2003
Thu Nov 27 15:29:18 MST 2003
Fri Nov 28 15:29:18 MST 2003
Sat Nov 29 15:29:18 MST 2003
Sun Nov 30 15:29:18 MST 2003
Mon Dec 01 15:29:18 MST 2003
Tue Dec 02 15:29:18 MST 2003
Wed Dec 03 15:29:18 MST 2003


-a
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