From: Robert Klemme <shortcutter@...>
Date: 2007-11-27T18:06:49+09:00
Subject: Re: Most elegant way to do this?

2007/11/27, Phrogz <phrogz@mac.com>:
> On Nov 26, 5:24 pm, Alex Young <a...@blackkettle.org> wrote:
> > rbysam...@gmail.com wrote:
> > > Are there any more elegant, concise, pithy, and more Rubyish ways of
> > > doing this?
> >
> > > def roll(number_of_dice)
> > >     sum = 0
> > >     number_of_dice.times do
> > >         sum += rand(5).next
> > >     end
> > >     sum
> > > end
> >
> > The Incredible Inevitable Inject:
> >
> > def roll(number_of_dice)
> >    (0...number_of_dice).inject(0){|m,r| rand(5)+m}
> > end
>
> You missed the +1 needed to take rand(5) to 1..6 instead of 0..5.

And everybody apparently missed 6 because rand(5) will yield *5*
values ranging in 0..4. :-))

> And I personally like 1..num_dice instead of 0...num_dice. And,
> finally, I sum things so often I usually have this lying around:
>
>   module Enumerable
>     def sum
>       if block_given?
>         inject(0){ |sum,obj| sum + yield(obj) }
>       else
>         inject(0){ |sum,obj| sum+obj }
>       end
>     end
>   end
>
> which makes the solution simply:
>   def roll(number_of_dice)
>     (1..number_of_dice).sum{ rand(5)+1 }
>   end

There is another one, that - at least theoretically - saves some
addition efforts:

require 'enumerator'

def roll(number)
  raise ArgumentError, "Negative!" if number < 0
  number.to_enum(:times).inject(number) {|s,| s + rand(6)}
end

I also threw in to_enum just for the fun of it. :-)

> In the vein of DRY code and unix tools, I strongly encourage everyone
> to be on constant vigil looking for bits of code that can be
> abstracted out to little atomic re-usable bits. After a while, coding
> is less like carving entire models from styrofoam, and more like
> snapping little Lego blocks together.

Absolutely!

Kind regards

robert

-- 
use.inject do |as, often| as.you_can - without end