From: Robert Klemme <shortcutter@...>
Date: 2007-09-12T06:10:03+09:00
Subject: Re: Thoughts on loops and stacks

On 11.09.2007 21:01, Todd A. Jacobs wrote:
> I was thinking about some of the design issues in my dice.rb script:
> 
>     http://www2.codegnome.org:59321/scripting/showscript.php?script=dice.rb
> 
> and one of the major issues is queueing. I'd like to ensure that
> selecting multiple URLs doesn't overwrite the current contents from the
> previous X selection, so I was thinking what I needed to do was
> implement a FIFO stack.

There is no such thing as a "FIFO stack".  A stack has LIFO semantics - 
a queue FIFO.

> My main issues are that I don't want to miss any X selections, but at
> the same time I don't want ruby running in such a tight loop that it
> sucks up excessive CPU time.
> 
> Right now, I'm doing:
> 
>     loop do;
> 	# grab X selection
>     	# time-consuming WWW::Mechanize stuff with selection
> 	sleep 0.3
>     end
> 
> which isn't really event driven. So, if I select several URLs in quick
> succession, only the URL in the X selection *the next time ruby looks at
> it* gets handled.
> 
> Suggestions?

If you have a single thread you can use an Array.

irb(main):022:0> q=[]
=> []
irb(main):023:0> 5.times {|i| q.push i}
=> 5
irb(main):024:0> until q.empty?; p q.shift; end
0
1
2
3
4
=> nil

Otherwise you can use a Queue as suggested by Ara.  From your problem 
description it seems you rather want a multithreaded solution.

Kind regards

	robert