From: Michael Neumann <mneumann@...>
Date: 2003-11-17T07:58:02+09:00
Subject: Re: Local Variable Scope in Ruby2

On Mon, Nov 17, 2003 at 07:21:15AM +0900, Harry Ohlsen wrote:
> Michael Neumann wrote:
> >Simple rule (Ruby 2.0): Block parameters are local to the block,
> >everything else is not.
> >
> >Consider the following example (Ruby 1.8):
> >
> >  a = 3
> >  [1,2].each do |a|
> >    p a
> >  end
> >  p a # => 2
> >
> >This problem is fixed with 2.0 (a => 3).
> 
> So, with the new semantics, how do we do things like ...
> 
> a = nil
> 
> some_collection.each do |x|
>   if some_condition
>      a = ...
>      break
>   end
> end

This will work exactly the same way as in Ruby 1.8. The assignment
inside the block will assign to the outer variable (a). Any assignment
inside a block with the exception of assignements to block parameter
variables (here x), will be to variables outside the block.

> Obviously, if we want "a" to end up being the same as one of the values in 
> the collection, there's probably some iterator other than "each" that will 
> allow for that.  However, if the value we want to give it is more complex 
> (or just plain different from the current value of x), what's the right 
> mechanism?
> 
> Sorry, I can't think of a concrete example this second, but I can remember 
> doing this kind of thing many times in the past ... mainly because it 
> always failed until I added the "a = nil" line :-).

In Rite you won't need a "a = nil" line anymore. "a=" inside the block
will automatically introduce a variable "a" outside the block.


Hopefully, I don't tell you something wrong :-)

Regards,

  Michael