From: Robert Klemme <shortcutter@...>
Date: 2011-07-28T21:29:36+09:00
Subject: Re: How do we read this line of code?

On Wed, Jul 27, 2011 at 10:54 PM, Stu <stu@rubyprogrammer.net> wrote:
> Hello abder.rahman.ali
>
> each is an important part of ruby and it is something people from
> other programming languages tend to find a bit confusing at first. It
> is basically a foreach loop( i.e. a loop that defeats the possibility
> of a off-by-one index based bug/error.) It is also a common design
> pattern.
>
> It should be read as:
>
> traverse each item in collection

Careful: we have no other context information and we do not know what
@x actually points to.  So we can only say something like

Invoke the block for each item which method @x.each yields.

> The final note about each. It is redesigned( overloaded) in many
> classes to work with a specific task of collections to aid the
> programmers with a common interface. If you ever create a class which
> acts as a collection it is common to redefine each to work within that
> class as well as other rubyisms such as to_s and so on. The more
> common the paradigm/syntax; the more fluid your mental and
> programmatic flow will work within the creation of your own programs.
> It also allows easy adoption( and adaption) for others to use your
> libraries.

But then again, it's not hard to create a class which follows the
Enumerable contract either:

class Silly
  include Enumerable

  def each
    rand(47).times { yield rand(11) }
    self
  end
end

Now with

@x = Silly.new

we can do

@x.each do |x| puts x end

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/