From: dblack@...
Date: 2007-09-11T21:03:23+09:00
Subject: Re: Bug in lambda?

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Hi --

On Tue, 11 Sep 2007, Pe=F1a, Botp wrote:

> Arggh, the scary part is you wont even know if you've been shot
> until you're dead --too late. I myself do not like block args (or
> any args for that matter) clobbering local, global, and instance
> vars. Surely, it is not the intent of the programmer to clobber
> them, nor is it an intuitive intent to peek on arg values from the
> outside (is that being obj-oriented?). I clobber what i clobber.
> When coding an arg var, surely i do not need to bother and question
> myself "will this var clobber other vars?". Ruby should help me on
> that, not put fear on it. I wonder what is the original intent of
> matz when he designed that feature.  It is scary. I've been hit by
> it. And now i have to be careful about naming my vars.

Is that bad? :-)

> Is shadowing
> arg vars really used much in practice? It is not a fun part of ruby
> if you ask me. or maybe, it is just too much fun for me. forgive the
> non-ruby-hacker, pls :(

But you always have to avoid clobbering variables:

   x =3D 1
   ...
   ...
   x =3D gets
   ...
   if x > 0    # blows up

I think the only hurdle is just realizing that:

   {|x| ... }

is an assignment to x. After that, it's no more dangerous or
error-prone than any other occasion when you have to choose a name for
a temporary (or not) variable and assign to it.


David

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