From: "ara.t.howard" <ara.t.howard@...>
Date: 2007-11-15T01:59:34+09:00
Subject: Re: Ordered Hash Usefulness


On Nov 13, 2007, at 1:53 PM, Devi Web Development wrote:

> What I really want to know is, is there some usefulness to ordered
> pairs I am missing?

i use mine (gem install alib, alib.orderedhash.new) all the time for  
generating reports in yaml.

   report = alib.orderedautohash.new

   report['name']['first'] = 'ara'
   report['name']['last'] = 'howard'

and this make the report print the same using

   y report

all the time.  if you use a hash the report will have varying order  
both within and between runs.  ruby queue uses this for job output,  
which looks like this:

-
jid: 4669
priority: 42
state: finished
submitted: 2007-11-14 09:07:36.124312
started: 2007-11-14 09:08:26.226328
finished: 2007-11-14 09:09:19.405155
elapsed: 53.178827
submitter: mussel.ngdc.noaa.gov
runner: clam.ngdc.noaa.gov
stdin: stdin/4669
stdout: stdout/4669
stderr: stderr/4669
pid: 16804
exit_status: 0
tag: eds
restartable: true
command: sif eds process_incoming /dmsp/nrt/subscriptions/eds/ 
incoming/F15200711141422.d.OIS
-
jid: 4670
priority: 42
state: finished
submitted: 2007-11-14 09:07:36.413314
started: 2007-11-14 09:08:26.342514
finished: 2007-11-14 09:11:44.703900
elapsed: 198.361386
submitter: mussel.ngdc.noaa.gov
runner: clam.ngdc.noaa.gov
stdin: stdin/4670
stdout: stdout/4670
stderr: stderr/4670
pid: 16860
exit_status: 0
tag: flo
restartable: true
command: sif flo process_incoming /dmsp/nrt/subscriptions/flo/ 
incoming/F15200711141422.d.OIS

it's *really* disorienting for users when jobs come out in different  
orders job to job, and the next run dumps out something different yet  
again.  make using 'diff' extremely frustrating.


the other use case is for something like a database tuple or a set of  
columns (mapped by name) displayed on an interface: you want to use  
them by name, for instance

   interface.columns['ssn']

but also want to say

   interface.columns.each{|k,c| render c}

and have that come out in order.  arrayfields (gem install  
arrayfields) skins this cat from the other direction: allowing normal  
arrays to support keyword acccess.

regards.

a @ http://codeforpeople.com/
--
it is not enough to be compassionate.  you must act.
h.h. the 14th dalai lama