From: David Alan Black <dblack@...>
Date: 2004-04-17T17:44:10+09:00
Subject: Re: New Local Variable Scope rule

Hi --

ts <decoux@moulon.inra.fr> writes:

> >>>>> "D" == David Alan Black <dblack@wobblini.net> writes:
> 
> D> ts <decoux@moulon.inra.fr> writes:
> 
> D> I admit I'm confused by this.  Is 'local' being introduced?  And if
> D> |a| is a block variable, isn't it local to the block anyway?
> 
>  [ruby-talk:63199]
> 
> >> and what do you do with this ?
> >> 
> >> Thread.new { a = 1 }    # like Proc or like lambda ?
> >> NewClass.new { a = 1 }  # like Proc or like lambda ?
> >> new_method { a = 1 }    # like Proc or like lambda ?
> 
> D> I'm not sure what you mean.  Do you mean what would I do if I were
> D> designing Ruby 2.0, 
> 
>  yes,
> 
> D>                    or what do I think Matz will have them do?  I
> D> don't know, since I still don't know the answer to the above (whether
> D> Proc and lambda will be different in this respect).  I think maybe you
> D> think that I know, but I don't :-)
> 
>  If you introduce a difference between Proc and lambda, what do you do
>  with the examples that I've given ?
> 
>  Thread will work like Proc or like lambda ?

Every code block will work (I assume!) like every other code block.
(Otherwise learning how to use blocks would be like learning irregular
verbs.)  So if Thread.new takes a block, that's exactly the same as
any other method taking a block.  

But that may or may not mean that Proc objects and lambdas, neither of
which (as I understand it) are the same thing strictly speaking as
code blocks (the thing that would be called a Block if there were a
Block class :-) behave the same as each other.

Going back to the original point (more or less): I'm just a little
perplexed by the whole idea of closures (blocks, Procs, lambdas)
having this compile-time effect on local variables in their context of
creation.  


David

-- 
David A. Black
dblack@wobblini.net