From: ara.t.howard@...
Date: 2006-08-31T02:52:58+09:00
Subject: Re: [RCR] Array.step

On Thu, 31 Aug 2006, Logan Capaldo wrote:

> require 'enumerator'
> class Array
>  def self.step(i, *a, &block)
>    b = block || lambda { |x| x }
>    i.to_enum(:step, *a).map(&b)
>  end
> end

you'll have to write almost as many lines as i did to make all of it work
though, still - i had forgotten about that:



harp:~ > cat a.rb
require 'enumerator'
class Array
  def self.step(i, *a, &block)
    b = block || lambda { |x| x }
    i.to_enum(:step, *a).map(&b)
  end
end

require 'irb/xmp'

xmp 'Array.step(0,4)'
xmp 'Array.step(0,-4)'

xmp 'Array.step(1,5,2)'
xmp 'Array.step(-1,-5,-2)'

xmp 'Array.step 2'
xmp 'Array.step -2'

xmp 'Array.step(0,7){|i| 2 ** i}'
xmp 'even = Array.step(9){|i| i.modulo(2).zero?}'



harp:~ > ruby a.rb
Array.step(0,4)
     ==>[0, 1, 2, 3, 4]
Array.step(0,-4)
     ==>[]                           # <- this one's wrong
Array.step(1,5,2)
     ==>[1, 3, 5]
Array.step(-1,-5,-2)
     ==>[-1, -3, -5]
Array.step 2
ArgumentError: wrong number of arguments
         from a.rb:17:in `step'
         from a.rb:17:in `step'
         from (irb):1
Array.step -2
ArgumentError: wrong number of arguments
         from a.rb:17:in `step'
         from a.rb:17:in `step'
         from (irb):1
Array.step(0,7){|i| 2 ** i}
     ==>[1, 2, 4, 8, 16, 32, 64, 128]
even = Array.step(9){|i| i.modulo(2).zero?}
ArgumentError: wrong number of arguments
         from a.rb:17:in `step'
         from a.rb:17:in `step'
         from (irb):1


regards.


-a
-- 
what science finds to be nonexistent, we must accept as nonexistent; but what
science merely does not find is a completely different matter... it is quite
clear that there are many, many mysterious things.
- h.h. the 14th dalai lama