From: dblack@...
Date: 2006-01-09T10:26:50+09:00
Subject: Re: Passing a hash of args

Hi --

On Mon, 9 Jan 2006, Jonathan Leighton wrote:

> On Mon, 2006-01-09 at 08:01 +0900, James Edward Gray II wrote:
>> Well, Hashes are unordered by definition, but as long as we declare
>> an order it's doable:
>>
>> >> time = {
>> ?>   :year => 2003,
>> ?>   :month => 03,
>> ?>   :day => 24
>> >> }
>> => {:month=>3, :year=>2003, :day=>24}
>> >> Time.local(*time.values_at(:year, :month, :day))
>> => Mon Mar 24 00:00:00 CST 2003
>
> Cool. Thanks everyone. I didn't realise you could do *myvar when calling
> a method as well as when defining them. I was basically looking for a
> way to do the following (which I've managed to solve without use of a
> hash):
>
> class Time
>  UNITS = [ :year, :month, :day, :hour, :min, :sec, :usec ]
>
>  def to_precision(unit)
>    args = []
>    0.upto(UNITS.index(unit)) { |unit| args <<
> method(UNITS[unit]).call }
>    Time.local(*args)
>  end
> end
>
> Is that a sensible way to do it?

I would do:

   send(UNITS[unit])

in preference to the method/call thing.  Maybe:

   args = (0..UNITS.index(unit)).map { |unit| send(UNITS[unit]) }


David


-- 
David A. Black
dblack@wobblini.net

"Ruby for Rails", from Manning Publications, coming April 2006!
http://www.manning.com/books/black