From: Adam Prescott <adam@...>
Date: 2011-05-24T19:08:13+09:00
Subject: Re: "Local variable within code blocks do not interfere with those outside the block"

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On Tue, May 24, 2011 at 10:45 AM, Kaye Ng <sbstn26@yahoo.com> wrote:

> " In Ruby 1.9, however, local variables used within code blocks will not
> interfere with local variables located outside of the block."
>
> I don't know if my code is wrong, but it looks to me like the local
> variable inside the code block DOES interfere with the local variable
> (with the same name) outside the code block.
>
> x = [1, 2, 3, 4, 5]
> var = 1
>
> x.each do
>       |number| (var = 10)
>     end
>
> puts var
>

It's affecting `var` because of the assignment, and because it's not an
argument to the block. You might find
http://ruby.runpaint.org/closures#block-local-variables useful to read
through. Also consider this:

a = 1; [2].each { |x| p a }; a              #=> 1; 1
a = 1; [2].each { |x| a = 10; p a }; a      #=> 10; 10
a = 1; [2].each { |a| p a }; a              #=> 2; 1
a = 1; [2].each { |a| p a; a = 10; p a }; a #=> 2; 10; 1

And with block-local variables in 1.9:

a = 1; [2].each { |;a| p a; }; a            #=> nil; 1
a = 1; [2].each { |;a| p a; a = 2; p a }; a #=> nil; 2; 1

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