From: "Hal E. Fulton" <hal9000@...>
Date: 2003-06-04T12:39:20+09:00
Subject: Re: case of sub! not working

----- Original Message ----- 
From: "Ian Macdonald" <ian@caliban.org>
To: "ruby-talk ML" <ruby-talk@ruby-lang.org>
Sent: Tuesday, June 03, 2003 10:31 PM
Subject: Re: case of sub! not working


> I understand your reasoning, but why is = any different to sub! ?
> If assignment (=) is just a method call with some syntactic sugar thrown
> in, then why is it that sub! tries to modify the outside environment,
> while = only modifies the singleton copy?

It's not really =, it's []=.

Real assignment is not a method. The []= 
*is* a method, one that is named so that it 
looks like an assignment and fits nicely 
inside our brains.

This is not nitpicking. In some languages,
x[y] would give you an lvalue, and then
you would call another method =. Here there
is only one method call, []=. 

Look at it this way: Suppose the [] and []=
methods were renamed to #get and #set.

You would not expect ENV.get(x).sub! to 
change ENV just because ENV.set(x) does so.
Makes sense?

Hal