From: Dan Doel <djd15@...>
Date: 2003-12-03T06:42:13+09:00
Subject: Re: Rite, Block locals and Autovivification

John Carter wrote:

>def histogram( enum)
>  # <--- Implicit hash = Hash.new(0) here
>  enum.each{|e| hash[e]+=1} # Hash autovivifies.
>  # Since hash autovivified we expect it to be available
>  # outside the block scope.
>  hash.keys.sort{|a,b| hash[a]<=>hash[b]}.each do |k|
>    puts "#{k}\t#{hash[k]}"
>  end
>end
>  
>
How do you know that hash needs to be a hash? Depending on what enum is,
it could be an array or something else even.

As I understand it, variables first assigned to in a block in 2.0 are 
equivalent to
variables in 1.8 with an implicit var = nil before the block, so they're 
visible
outside the block.  Autovivifying to something other than nil seems more 
dangerous
than it would be worth to me.

- Dan