From: botp <botpena@...>
Date: 2011-02-25T14:53:39+09:00
Subject: Re: why is $1 in a grep() equal to nil?

On Fri, Feb 25, 2011 at 4:59 AM, 7stud -- <bbxx789_05ss@yahoo.com> wrote:
> class Computer
>    def initialize(an_id, data_source)
>        @id = an_id
>        @ds = data_source
>
>        @ds.methods.grep(/^get_(.+?)_info$/) do
>
>            puts "-->#{$1}<---"
>
>            Computer.send(:define_method, $1.to_sym) do

inside this block, your code references $1 itself.
but what you really want is that $1 be evaluated first before the
block generation.

>                puts "****" + $1 + "****"   #***NIL NIL NIL NIL
>
>                info = @ds.send("get_#{$1}_info".to_sym)
>                price = @ds.send("get_#{$1}_price".to_sym)
>
>                alert = ""
>                if price > 100
>                    alert = "*"
>                end
>
>                puts "#{alert} #{info} #{price}"
>             end
>        end
>    end


try this (brute force) way just to get the idea,

class Computer
   def initialize(an_id, data_source)
       @id = an_id
       @ds = data_source

       @ds.methods.grep(/^get_(.+?)_info$/) do


          puts "-->#{$1}<---"
          eval <<-EVILHERE
           Computer.send(:define_method, $1.to_sym) do
               #puts "****" + ($1) + "****"   #***NIL NIL NIL NIL

               info = @ds.send("get_#{$1}_info".to_sym)
               price = @ds.send("get_#{$1}_price".to_sym)

               alert = ""
               if price > 100
                   alert = "*"
               end

               puts "\#{alert} \#{info} \#{price}"
            end
          EVILHERE
       end
   end
end


best regards -botp