From: ahoward <ahoward@...>
Date: 2003-02-03T01:11:21+09:00
Subject: Re: Local variables & blocks

On Sun, 2 Feb 2003, Yukihiro Matsumoto wrote:

> I agree with you.  I was insane when I designed this rule.  That's why I
> propose the change.  But I don't think we can just drop block local
> variables like yours, since we have Proc (some kind of anonymous function),
> we need some kind of local variables of their own.

insane?  i don't think so to me this is _natural_ as in Cs

  int x;
  {
    x = 42;
  }

vs

  int x;
  {
    int x;
    x = 42;
  }

this is expected when one realizes ruby's lhs statement do both declaration in
current scope and definition in current scope.

how about some simple means on introducing a local scope?  a new
keyword/method?  perhaps 'scope/end' and '{{/}}'.  this could allow the
programmer to work as wished, added to your current plan one would end up with
:

  [4,2].each { |c|
    s << c.to_s
  }
  puts s	  # >> 42

  [4,2].each {{ |c|
    s << c.to_s
  }}
  puts s

  NameError: undefined local variable or method `s' for #<Object:0x401909fc>

maybe that syntax is no good, but what would be the problem of allowing
programmers to introduce scopes (most languages do)?  this would allow to the
introduce your new plan, and in cases (like threads) or for people where it
might be an imperfect fit you could say 'just introduce a scope and it will be
as before'.  i guess one could simply use guy's 'local' method, but it would
be nice if that were built in for people who like scopes.  using this, the
default for thread might be to introduce a new scope - there are some cases
where POLS means blocks should start a new scope.

-a

-- 

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