Thoughts on loops and stacks

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.

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?

On Sep 11, 2007, at 1:01 PM, Todd A. Jacobs wrote:

Suggestions?

require ‘thread’

q = Queue.new

consumer = Thread.new do
while(( pair = q.pop ))
event, data, *ignored = pair
case event
when :something
when :something_else
end
end
end

q.push [:somthing, ‘some data’]

a @ http://drawohara.com/

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.

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

On Sep 11, 2007, at 17:10 , Robert K. wrote:

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.

Did you try this?

array = [1,2,3,4,5]
=> [1, 2, 3, 4, 5]

array.shift
=> 1

array
=> [2, 3, 4, 5]

array << 6
=> [2, 3, 4, 5, 6]

array
=> [2, 3, 4, 5, 6]

array.shift
=> 2

~Wayne

s///g
Wayne E. Seguin
Sr. Systems Architect & Systems Administrator

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