From: Guillaume Marcais <guslist@...>
Date: 2003-07-09T05:09:40+09:00
Subject: Re: Array.each

On Tue, 2003-07-08 at 15:00, Berger, Daniel wrote:
> 
> > Gentelmans:  ........(There are any woman around there ?)
> > 
> > I would love  to be able to do:
> > 
> > 
> > a=(1..10)
> 
> With this code, 'a' becomes a single Range.  Try: a = *1..10.
> 
> > a.each {| x , y|  p x }
> > 
> > 1
> > 3
> > 5
> > 7
> > 9
> 
> You'll have to redefine each() to yield two elements instead of one in order
> to get this behavior.  Or you could just use step:
> 
> 0.step(a.length,2){ |i| p a[i] }
>  
> > (IMHO ...  following the principle of the least surprise..may  it 
> > should  be a native behavior .)
> 
> You mean Ruby should automatically yield as many parameters as the block
> expects?  You'll have to talk to Matz about that one. :)

Something like that?

[gus@comp ex]$ cat eachn.rb
module Enumerable
  def each_n(&b)
    i = []
    n = b.arity
    n = -n if n <= 1
    k = n
    self.each { |x|
      i << x
      k -= 1
      if k <= 0
        b.call(*i)
        i = []
        k = n
      end
    }
    unless i.empty?
      i += Array.new(n - i.length)
      b.call(*i) unless i.empty?
    end
  end
end

if __FILE__ == $0
  (0..10).each_n { |x| puts "x %s" % x.inspect }
  (0..10).each_n { |x, y| puts "x %s y %s" % [x.inspect, y.inspect] }
  (0..10).each_n { |x, y, z| puts "x %s y %s z %s" % [x.inspect,
y.inspect, z.inspect] }
  [].each_n { |x, y| puts "Huh?" }
end

[gus@comp ex]$ ruby eachn.rb
x 0
x 1
x 2
x 3
x 4
x 5
x 6
x 7
x 8
x 9
x 10
x 0 y 1
x 2 y 3
x 4 y 5
x 6 y 7
x 8 y 9
x 10 y nil
x 0 y 1 z 2
x 3 y 4 z 5
x 6 y 7 z 8
x 9 y 10 z nil

Guillaume.

 
> Regards,
> 
> Dan
>