From: Kristof Bastiaensen <kristof@...>
Date: 2004-05-01T22:59:01+09:00
Subject: Re: Lazy evaluation (evil)

On Sat, 01 May 2004 22:15:52 +0900, ts wrote:

>  Well, in the original message from matz, there are 2 possibilities
>   * do ||
>   * let
> 
>   [ruby-talk:63199]
> 
>  Now, what do you expect with this (for `a' and `b') ?
> 
>    1.times do |i|
>       let a = i
>       let b = a + 1
>    end
> 
> 
> Guy Decoux

Hi,
Both solutions look good to me.  The advantage of using do would 
be that you could see the scope of the variable more clearly.

Let however would require less typing, because the above would 
have been:

1.times do |i|
  do |a| a = i
    do |b| b = a + 1; end
  end
end

But on the other side, block local variables are probably
mostly only useful for closures, so maybe a let keyword is not
necessary.

The local construct may be nice for initializing block local
vars:

local(1, 2) do |i, a|
  puts i + i
  puts a * a
end
=> 2
=> 4

do without anything before it will then initialize to nil.

Kristof