From: Robert Dober <robert.dober@...>
Date: 2008-05-23T17:50:41+09:00
Subject: Re: Prevent ruby constant variables from changing?

On Thu, May 22, 2008 at 11:12 PM, Sebastian Hungerecker
<sepp2k@googlemail.com> wrote:
> Jeremy Hinegardner wrote:
>> I didn't know that what
>> is returned from the end of a class ... end and module .. end block is
>> NilClass.
>
> It's not. A  class/module ... end  block returns the value of the last
> expression in it. So
> module C
>  X = 42
> end.freeze
> calls freeze on 42
Now I am a big user of 42 but you surely made a mistake here, freeze
has to be called on 32, right? (Hint: here in Europe we rather call it
on 0).
Well this is offtopic, let us get ontopic again ;)
I feel it is interesting how many different views we got here on the subject...

look at these semantics
517/17 > irb
irb(main):001:0> class A
irb(main):002:1> end
=> nil
irb(main):003:0> B = A
=> A
irb(main):004:0> class B
irb(main):005:1> def a; 42 end
irb(main):006:1> end
=> nil
irb(main):007:0> A.new.a
=> 42
irb(main):008:0> B.name
=> "A"

I just feel to think more seriously now never to use "class X" again,
I want to avoid the very subtle inconsistencies it implies but I
really hate, that after

C = Class::new
C.name equals "C".
This is the first time ever since I discovered that blocks cannot have
block parameters that I feel that Ruby stands in my way, no it is
worse, Ruby overrules me, decides for me, that is *soooo* untypical
for Ruby. And furthermore the former went away in 1.9 while the later
did not. I guess I will write an RCR right away.

You cannot even trick the parser!!!

irb(main):001:0> C = _ = Class::new
=> C
irb(main):002:0> C.name
=> "C"

but finally

irb(main):006:0> _ = Class::new
=> #<Class:0xb7d5af90>
irb(main):007:0> _.name
=> ""
irb(main):008:0> X = _
=> ""
irb(main):009:0> X.name
NoMethodError: undefined method `name' for "":String
        from (irb):9
        from :0
irb(main):010:0>

I get where I wanted :).

>
> HTH,
> Sebastian
> --
> NP: Depeche Mode - Master And Servant
> Jabber: sepp2k@jabber.org
> ICQ: 205544826
>
>



-- 
http://ruby-smalltalk.blogspot.com/

---
Whereof one cannot speak, thereof one must be silent.
Ludwig Wittgenstein