From: 7stud -- <bbxx789_05ss@...>
Date: 2011-03-26T08:31:38+09:00
Subject: Re: How to get the value of a singleton class?

Robert Dober wrote in post #989182:
> On Fri, Mar 25, 2011 at 1:23 PM, Joey Zhou <yimutang@gmail.com> wrote:
>>
>> x.rb:3:in `singletonclass': undefined local variable or method `str' for
>> #<Class:#<String:0x1625bf8>> (NameError)
>>
>> How can I get the value of str("ABC") within the class << str;...;end
>
> your problem is that class << x...end  is *not* a closure
>
> x= 42
> class << whatever # I disassociate x and whatever for the general case
>   x # No Method Error as we are *not* in a closure here
> end
>
> But there is a workaround, an idiom you will find quite often in Ruby
> metaprogramming
>
> x=42
> class << whatever; self end.module_eval do
>   p x # Works like charm as this *is* a closure
> end
>

...but that is a ridiculous construct.  You are creating a block for 
module_eval() in order to see the local variable x.  Well guess what? 
You don't need a block to see x:

x = 42

class << whatever
  self
end

puts x

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