From: Robert Evans <robert.evans@...>
Date: 2006-11-27T07:13:40+09:00
Subject: Re: REXML and Date interaction

Hi,

Thanks for running it, indeed that broken version works, and I  
must've corrupted my irb session. So, I tried it again and discovered  
more precisely the problem. If I include REXML in the class instead  
of explicitly specifying REXML::Document, then I get the problem.  
Which, I can just "not do that" for now, but it is still curious what  
is happening. Here is a version that seems to produce the error still.

Thanks for the sanity check,

Bob Evans



Better Broken
=============
#!/usr/bin/env ruby

require 'rexml/document'
require 'date'

class DateFun
## BEGIN Different
include REXML
## END Different

   def parse(xml)
## BEGIN Different
     doc = Document.new(xml)
##End Different

     elems = doc.root.get_elements('//body/dateelement[@date]')
     elems.map { |s|
       s.attributes["date"].to_s
     }.sort
   end

   def sorted_dates_from(xml)
     sorted_dates = parse(xml)
     sorted_dates.map { |d| Date.parse(d)}.sort
   end
end

xmlDates = <<HERE
<body><dateelement date="12/28/1973"/><dateelement date="02/06/1970"/ 
 ><dateelement date="02/05/1954"/></body>
HERE

sorted_dates = DateFun.new.sorted_dates_from(xmlDates)
sorted_dates.each { |d| puts d.to_s}


Produces
===============
./brokendate.rb
./brokendate.rb:18:in `sorted_dates_from': undefined method `parse'  
for "2005/224":String (NoMethodError)
         from ./brokendate.rb:18:in `sorted_dates_from'
         from ./brokendate.rb:26



On Nov 26, 2006, at 1:54 PM, dblack@wobblini.net wrote:

> Hi --
>
> On Mon, 27 Nov 2006, Robert Evans wrote:
>
>> Hi,
>>
>> I have a problem parsing dates from XML. I have this little  
>> program which produces an error, and I was able to fix it by  
>> moving the date parsing into a class that is distinct from the xml  
>> processing. Below is a broken version and the error it prints, and  
>> then a working version with the correct output. I would be  
>> grateful if anyone could explain what is going wrong here. It  
>> looks like it turns the class Date into a string Constant.
>
> Your broken version worked for me.  What version of Ruby are you
> using?
>
>
> David
>
> -- 
>                   David A. Black | dblack@wobblini.net
> Author of "Ruby for Rails"   [1] | Ruby/Rails training &  
> consultancy [3]
> DABlog (DAB's Weblog)        [2] | Co-director, Ruby Central,  
> Inc.   [4]
> [1] http://www.manning.com/black | [3] http:// 
> www.rubypowerandlight.com
> [2] http://dablog.rubypal.com    | [4] http://www.rubycentral.org
>