From: Bill Kelly <billk@...>
Date: 2002-12-11T08:21:43+09:00
Subject: Re: Seeking Ruby Samadhi

Hi,

From: "Jake" <jsuntheimer@neo.rr.com>

> class Array
>   def each2
>     each {|value| puts value}
>   end
> end
> [1, 2, 3].each2
> 
> 
> **HOW IN THE NAME OF ALAN TURING DOES _each2_ PASS _value_ TO
> _each_***?!?!

:)  It's like:

class Array
  def each2
    self.each {|value| puts value}
  end
end

where each is talking to an implicit "self".  

Other variations:

class Array
  def each3
    0.upto(length - 1) {|value| puts value}
  end
  def each4
    (0...length).each {|value| puts value}
  end
end

In the above, length is self.length implicitly.  The values
are coming from iterators based on values obtained from "self",
rather than passed in from each2, each3, or each4...


Another example, replacing "each" itself with our own version:

irb> class Array
irb>   def each
irb>     0.upto(length - 1) {|idx| yield self.at(idx) }  # could also use each_index {}
irb>     self
irb>   end
irb>   def each2
irb>     each {|value| puts value}
irb>   end
irb> end
nil
irb> [1,2,3].each2
1
2
3

...in case it's useful to see how "each" itself might be implemented...


Hope this helps,

Bill