From: Robert Klemme <shortcutter@...>
Date: 2007-06-08T22:15:07+09:00
Subject: Re: What about a 'series' type?

On 08.06.2007 14:27, Robert Dober wrote:
> On 6/8/07, Robert Klemme <shortcutter@googlemail.com> wrote:
>> On 07.06.2007 23:12, Robert Dober wrote:
>> > On 6/7/07, Robert Klemme <shortcutter@googlemail.com> wrote:
>> >> On 07.06.2007 21:41, Robert Dober wrote:
>> >> > On 6/7/07, Robert Klemme <shortcutter@googlemail.com> wrote:
>> >> >
> 
> First of all thx for your time but I am not a quick learner :(
> 
> Obviously I am (or rather was )missing something very basic and if I
> understand correctly that very basic is that method_invocations are on
> copies of the local data, in each thread, is this *really* true? Well
> you already showed with an example.

Even more fine granular: there is one copy of local variables /per 
invocation/ of a method.  You can play a bit with this to see the effect:

def recurse(i = 5)
   s = "#{Thread.current.inspect} #{i} "
   print s, "enter\n"
   recurse(i - 1) if i > 0
   print s, "leave\n"
end

If you then do something like

2.times { Thread.new { recurse } }

You'll notice how values for "enter" decrease nicely and increase for 
"leave" per thread.  Internally Ruby has a stack that stores all local 
variables (including method arguments) and every time a method is 
invoked a new stack frame is put on the stack which stores all those 
values.  This is basically how most popular programming languages work.

> Hopefully I can put this into work tonight, gotta go back to work
> here, hopefully this weeks Ruby Quiz will be boooring, please James ;)

:-)

Kind regards

	robert