From: Ruby Freak <twscannell@...>
Date: 2008-03-26T12:44:54+09:00
Subject: Re: Passing params to Map method

Thank you David,
I stand corrected (actually I'm sitting)

So.. I have been re-reading the best darn Ruby/Rails book on the
planet (Ruby for Rails of course! which I already read cover to cover
once) and I am still a bit confused but it's getting better.
Maybe someone could be so kind as to critique my comments below about
what I think is happening. I have been studying this little bit code
for about 6 .. no 8, hours and hopefully, I have most of it correct.
(personally I find it irritating when people ask questions without
putting any personal effort into finding the answers themselves)

module Rails
  module Info
    mattr_accessor :properties           #module level property
assessor (getter and setter)
    class << (@@properties = [])         #Open up Array class def to
add methods (class << object), object == an Array
      def names                          #define
Array.properties.names method
        map {|(name, )| name}            #read code block to return
array comprised of first half of [name, value]
      end

      def value_for(property_name)       #define
Array.properties.value_for("name param") method
        find {|(name, )| name == property_name}.last rescue nil
#return value part of [name, value] for sent name param
      end
    end                                  #close Array class def

    class << self #:nodoc:               #open "Info" class def to add
methods
      def property(name, value = nil)    #define property "setter"
except the yield makes it a "getter"
        value ||= yield                  #if value is nil, yield name
to code block in names and value_for
        properties << [name, value] if value  #push [name, value]
array into @@properties array
      rescue Exception                   #ignore error?
      end
      ...

What I think is happening is the new "Info.properties" accessor is
cleverly leveraging self.property as a method to both set a new
property into @@properties and to return (yield) just the name when
the parameter passed to the code block is just the first half of the
array (name, ). Just understanding that after 8 months and thousands
of hours and reading thousands of pages of books is really exciting
for me.

I am a little iffy on the "class << (@@properties = [])" opening up
the Array object, but it fits the rule.(class << object)

if that is true, it is pretty cool code. (it's pretty cool even if I
am wrong) Ruby has quite a learning curve, especially for a VB guy.

Thanks again.