From: Dave Thomas <Dave@...>
Date: 2000-10-15T21:29:54+09:00
Subject: [ruby-talk:5543] Re: Some newbye question

matz@zetabits.com (Yukihiro Matsumoto) writes:

> 3 possible solution in my mind for the future:
> 
>   (1) local variables in the block parameters be valid only in the
>       surrounding block.  I think Davide proposed this one.  This
>       violates (a), and introduces incompatibility (small?).  This is
>       not perfect since the problem remains for non parameter local
>       variables.

If I had a vote, I'd go for this one, as it seems cleanest. 

Non-parameter variables are fine as they are, as they make closures
possible.

Parameters are different, though. A parameter is not a true variable
per-se, but instead is a placeholder for one. The fact that a
parameter shares a name with another variable in the enclosing scope
is just a coincidence.


I guess an alternative would be to make _all_ variables and parameters 
local to the block, and then introduce some kind of operator which
says "scope this variable outside the block" so that closures would
work. This has the benefit of making scope-sharing explicit, but is
would break a whole heap of code.


Regards


Dave