From: "Thomas B." <tpreal@...>
Date: 2008-09-11T17:34:28+09:00
Subject: Re: Blocks and scoping question

Mischa Fierer wrote:
> Hello,
> 
> The following makes sense to me:
> 
> lambda {|x| puts x; [1,2].collect{|x| x+1} }.call("aaa")
> aaa
> => [2, 3]
> 
> The following does not so much:
> 
> lambda {|x| puts x; [1,2].collect{|x| x+1}; puts x }.call("aaa")
> aaa
> 2
> => nil
> 
> Why is the final puts x not return a?

It's because the x in collect{|x| ...} in fact uses the variable x that 
previously contained your "aaa", because it is already defined in this 
scope. If x wasn't defined at the point of calling collect, then x 
inside collect's block would be a separate variable each iteration.

This is going to change in Ruby 1.9, and block variables will always be 
separate from variables visible in the scope.

TPR.
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