From: Brian Candler <b.candler@...>
Date: 2008-10-01T17:32:56+09:00
Subject: Re: ruby1.9 block scope

Daniel DeLorme wrote:
> 1   collection.each do |element|
> 2     changed = true if element.change
> 3   end
> 4   do_something if changed
> 
> Are you really saying that upon reading line 4 you have to backtrack to
> line 2 in order to understand this code?

I think the point is more this:

class Foo
  attr_reader :changed

  def update
    collection.each do |element|
      element << "\n" if changed      # <<<<
    end
    ...
    ...
    ...
    collection.each do |element|
      changed = true if element.change
    end
  end
end

At the marked line, you can't tell whether 'changed' is a local variable 
or a method call on this object until you have read forward to the end 
of the method. For me, this is horrid.

Perhaps more importantly though, as far as I can see it makes irb pretty 
useless, since it can't predict the future. What's supposed to happen 
when you type this, one line at a time?

def tmp; "hello"; end
m = lambda { |x| tmp + x }
m[" world"]
tmp = "goodbye"
m[" world"]

This particular example may be somewhat contrived, but if code behaves 
differently in irb than when read from a source file, that would be 
horrid (and difficult to explain) too.

Regards,

Brian.
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