From: Walton Hoops <walton@...>
Date: 2009-10-03T01:50:32+09:00
Subject: Re: Control of Priority Queue Order? And size limits on queues?

On Thu, 01 Oct 2009 23:38:46 -0600, Mason Kelsey <masonkelsey@gmail.com>  
wrote:

> Thanks for the reply Christopher.
>
> No, it would still be a priority queue if I could control the order of
> MATCHING key values.  I still want the unmatched key values to be sorted
> automatically in order ascending or descending as I push new entries onto
> the queue.

Your focusing on the definition of Priority, and ignoring the Queue part
A queue is defined as a First-in-First-out (FiFo) data structure.  In other
words if I add 'B' to the Queue, then 'A', when I read from the Queue I  
get 'B'
then 'A'.

A priority queue changes this behavior, in that items with the higher  
priority
go first. Thus assuming 'B1' and 'B2' are considered equal priority, if I  
add
'B1' to the Queue, then 'B2', when I read the Queue I MUST first get 'B1'  
then
'B2' or it ceases to be a Queue.

A Stack on the other hand in a First-in-Last-out (FiLo) data structure. So  
if I
add 'B1' then 'B2' and read the Stack, I get out 'B2' then 'B1' in that  
order.

Thus, what you are looking for is a Priority Stack, not a Priority Queue.

To answer your question, I don't know of a pre-built Priority Stack for  
Ruby,
but that doesn't mean it doesn't exist.

Hope this clears things up!