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comp.lang.ruby

What does $var mean?

Magicloud Magiclouds

2/1/2008 9:29:00 AM

Hello,
I mean what kind of variable is $var? What is its 'domain'?

Thanks.
3 Answers

Stefano Crocco

2/1/2008 9:40:00 AM

0

Alle Friday 01 February 2008, Magicloud Magiclouds ha scritto:
> Hello,
> I mean what kind of variable is $var? What is its 'domain'?
>
> Thanks.

It's a global variable. This means it's visible from everywhere in your
program.

Stefano Crocco

Robert Klemme

2/1/2008 10:00:00 AM

0

2008/2/1, Stefano Crocco <stefano.crocco@alice.it>:
> Alle Friday 01 February 2008, Magicloud Magiclouds ha scritto:
> > Hello,
> > I mean what kind of variable is $var? What is its 'domain'?
> >
> > Thanks.
>
> It's a global variable. This means it's visible from everywhere in your
> program.

Sometimes it's only thread global:

10:56:03 /cygdrive/c/SCMws/RKlemme/OPSC_Gold_bas_dev_R1.2_cug
$ ruby -e '(1..2).map {|i| Thread.new(i) {|a| /\d+/ =~ a.to_s; 2.times
{p [Thread.current, a, $&];}}}.each {|th| th.joi
n}'
[#<Thread:0x1002fd7c run>, 1, "1"]
[#<Thread:0x1002fbd8 run>, 2, "2"]
[#<Thread:0x1002fd7c run>, 1, "1"]
[#<Thread:0x1002fbd8 run>, 2, "2"]
10:59:31 /cygdrive/c/SCMws/RKlemme/OPSC_Gold_bas_dev_R1.2_cug
$

Kind regards

robert


--
use.inject do |as, often| as.you_can - without end

Thomas Wieczorek

2/1/2008 10:02:00 AM

0

Hi!

On Fri, Feb 1, 2008 at 10:29 AM, Magicloud Magiclouds
<magicloud.magiclouds@gmail.com> wrote:
> Hello,
> I mean what kind of variable is $var? What is its 'domain'?
>

Every variable with a $ is a global variable. You can learn more about
variables here:
http://phrogz.net/ProgrammingRuby/tut_classes.html#classesobjectsan...

Or as _why puts it at http://poignantguide.net/ruby/chap...:
"Most variables are rather temporary in nature. Some parts of your
program are like little houses. You walk in and they have their own
variables. In one house, you may have a dad that represents Archie, a
travelling salesman and skeleton collector. In another house, dad
could represent Peter, a lion tamer with a great love for flannel.
Each house has its own meaning for dad.

With global variables, you can be guaranteed that the variable is the
same in every little house. The dollar sign is very appropriate. Every
American home respects the value of the dollar. We're crazy for the
stuff. Try knocking on any door in America and hand them cash. I can
guarantee you won't get the same reaction if you knock on a door and
offer Peter, a lion tamer with a great love for flannel."