From: Intransition <transfire@...>
Date: 2010-08-31T04:45:17+09:00
Subject: Re: Time#round in 1.9



On Aug 30, 3:13 pm, Kirk Haines <wyhai...@gmail.com> wrote:
> On Mon, Aug 30, 2010 at 12:42 PM, Intransition <transf...@gmail.com> wrote:
> > Anyone know about Time#round in 1.9. Apparently it exists but it seems
> > to do nothing but eat up cpu cycles.
>
> >  ruby-1.9.2-p0 > t = Time.new
> >   => 2010-08-30 14:34:03 -0400
> >  ruby-1.9.2-p0 > t.round(100000)
> >   => 2010-08-30 14:34:03 -0400
> >  ruby-1.9.2-p0 > t.round(1000000)
> >   => 2010-08-30 14:34:03 -0400
>
> A voice was heard to utter: "Use the source, Luke! Errr, uh, Trans.
> Oh, and the docs!"

The docs would be nice, but ri has been broken for months[1] and I
could not find any mention of the method online.

But you are right I could have checked the source.

> /*
>  * call-seq:
>  *   time.round([ndigits])   -> new_time
>  *
>  * Rounds sub seconds to a given precision in decimal digits (0 digits
> by default).
>  * It returns a new time object.
>  * _ndigits_ should be zero or positive integer.
>  *
>  *     require 'time'
>  *
>  *     t = Time.utc(2010,3,30, 5,43,"25.123456789".to_r)
>  *     p t.iso8601(10)           #=> "2010-03-30T05:43:25.1234567890Z"
>  *     p t.round.iso8601(10)     #=> "2010-03-30T05:43:25.0000000000Z"
>  *     p t.round(0).iso8601(10)  #=> "2010-03-30T05:43:25.0000000000Z"
>  *     p t.round(1).iso8601(10)  #=> "2010-03-30T05:43:25.1000000000Z"
>  *     p t.round(2).iso8601(10)  #=> "2010-03-30T05:43:25.1200000000Z"
>  *     p t.round(3).iso8601(10)  #=> "2010-03-30T05:43:25.1230000000Z"
>  *     p t.round(4).iso8601(10)  #=> "2010-03-30T05:43:25.1235000000Z"
>  *     p t.round(5).iso8601(10)  #=> "2010-03-30T05:43:25.1234600000Z"
>  *     p t.round(6).iso8601(10)  #=> "2010-03-30T05:43:25.1234570000Z"
>  *     p t.round(7).iso8601(10)  #=> "2010-03-30T05:43:25.1234568000Z"
>  *     p t.round(8).iso8601(10)  #=> "2010-03-30T05:43:25.1234567900Z"
>  *     p t.round(9).iso8601(10)  #=> "2010-03-30T05:43:25.1234567890Z"
>  *     p t.round(10).iso8601(10) #=> "2010-03-30T05:43:25.1234567890Z"
>  *
>  *     t = Time.utc(1999,12,31, 23,59,59)
>  *     p((t + 0.4).round.iso8601(3))    #=> "1999-12-31T23:59:59.000Z"
>  *     p((t + 0.49).round.iso8601(3))   #=> "1999-12-31T23:59:59.000Z"
>  *     p((t + 0.5).round.iso8601(3))    #=> "2000-01-01T00:00:00.000Z"
>  *     p((t + 1.4).round.iso8601(3))    #=> "2000-01-01T00:00:00.000Z"
>  *     p((t + 1.49).round.iso8601(3))   #=> "2000-01-01T00:00:00.000Z"
>  *     p((t + 1.5).round.iso8601(3))    #=> "2000-01-01T00:00:01.000Z"
>  *
>  *     t = Time.utc(1999,12,31, 23,59,59)
>  *     p (t + 0.123456789).round(4).iso8601(6)  #=>
> "1999-12-31T23:59:59.123500Z"
>  */
>
> Below that is a short, simple to follow implementation.  You are
> telling it to round to 100000 or 1000000 digits. That's probably not
> what you mean?

I see, so it only rounds sub-seconds per digit. That's too bad,
Facets' #round method could round to any second. I have to rename.

Thanks.

[1] /home/trans/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/rdoc/ri/
driver.rb:909:in `load_method': undefined method `[]' for nil:NilClass
(NoMethodError)