From: Daniel DeLorme <dan-ml@...42.com>
Date: 2008-09-30T17:56:26+09:00
Subject: Re: ruby1.9 block scope

Mike Gold wrote:
> Making the scope of x contingent upon what comes later would result, I 
> believe, in extreme confusion.
> 
> Let's say Foo is a large class.  Joe Schmo, who did not write Foo, comes 
> along and adds some code to the bottom, such as the 'x = 45' in your 
> example.  Suddenly there is a bug in Foo.  It seems impossible to Joe, 
> but there it is.  He wonders if it is caused by the recent sunspots.  He 
> wraps his computer in tin foil, but to no avail.  The tests for bar and 
> baz still fail as a result of his (obviously, to him) unrelated change.
> 
> This was the 'tall' case, but there is also the 'wide' case of deeply 
> nested scopes.  An equal helping of confusion applies here too.
> 
> One might argue that when 'x = 45' appears before bar and baz, this 
> _already_ changes the meaning of bar and baz.  But the situation here is 
> entirely different, in my mind.  Don't most of us read code from top to 
> bottom?

Yes, I would argue that, and I believe most of us don't *add* new code 
always at the bottom of the file. If the bar and baz methods are defined 
at the bottom and Joe Schmo adds x = 45 at the top, he has the same 
problem. I really don't see how it's any different; it's symmetric. Bugs 
happen, and it's possible to come up with "problems cases" for 
absolutely every feature in ruby, but that doesn't mean they turn out to 
be problems in reality.

I must ask: is this confusing to *you* or are you trying to "protect" a 
hypothetical Joe Schmo? I'll take the hypothetically confused Joe Schmo 
over the very *real* confusion of every ruby newbie who wonders why his 
local var has disappeared after the loop.

--
Daniel