From: dblack@...
Date: 2007-07-25T19:55:23+09:00
Subject: Re: Static variables in Ruby.

Hi --

On Wed, 25 Jul 2007, Robert Dober wrote:

> On 7/24/07, Joel VanderWerf <vjoel@path.berkeley.edu> wrote:
>> Nobuyoshi Nakada wrote:
>> > Hi,
>> >
>> > At Tue, 24 Jul 2007 17:40:57 +0900,
>> > Marcin Tyman wrote in [ruby-talk:261483]:
>> >> Is any way to define static variables over function? As class static
>> >> variables there is possible to define a static class variable as
>> >> @@name_of_var. But I'm not sure if Ruby let define such variables in
>> >> functions (like in C/C++)
>> >
>> >   def foo(x)
>> >     (0..0).instance_eval{x,@x = @x,x}
>> >     x
>> >   end
>> >   3.times{|i|p foo(i)} #=> nil, 1, 2
>> >
>> > The literal object can be Float, Regexp or Bignum, but Range
>> > would be faster a bit.
>> >
>> 
>> Interesting. That is because Float, Regexp, and Bignum are instantiated
>> per scope, right?
>> 
>> Sometimes a little abstraction leakage can be useful!
>> 
>> --
>>        vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407
>> 
>> 
> I did not believe this,and why should I?
> But it seems to be true ;)
> def foo(x)
> (0..0).instance_eval{x,@x = @x,x}
> x
> end
>
> 3.times{ |i| puts foo(i) }
> (0..0).instance_eval{@x=42}
> 3.times{ |i| puts foo(i) }
>
> Run this for a pleasant surprise :)

I get the same result with or without the line between the two times
calls.  Are you seeing it output 42?


David

-- 
* Books:
   RAILS ROUTING (new! http://www.awprofessional.com/title/0321509242)
   RUBY FOR RAILS (http://www.manning.com/black)
* Ruby/Rails training
     & consulting:  Ruby Power and Light, LLC (http://www.rubypal.com)