From: Christian Neukirchen <chneukirchen@...>
Date: 2006-05-08T22:57:21+09:00
Subject: Re: REXML exception rescuing

Eli Bendersky <eliben@gmail.com> writes:

> Ross Bamford wrote:
>> On Mon, 2006-05-08 at 03:21 +0900, Eli Bendersky wrote:
>>> When REXML throws ParseException, a whole load information is spilled 
>>> into msg. Although this is useful for debugging, it hardly is an option 
>>> for a "real-life" application that just has to notify the user of an 
>>> error in his .xml file in the friendliest way possible.
>>> 
>>> How can I get just the "malformed XML: missing tag start" part (plus the 
>>> line in the file) without all the stack trace and the information that 
>>> comes after it, which for some reason is repeated twice. Is this 
>>> possible without deconstructing the raised msg ?
>> 
>> This is probably a bit naive but maybe will be a start:
>> 
>> begin
>>   doc = REXML::Document.new File.new('bad.xml')
>> rescue REXML::ParseException => ex
>>   puts "Failed: #{ex.message[/^.*$/]} (#{ex.message[/Line:\s\d+/]})"
>> end
>
> Ross,
>
> Thanks for your suggestion, it was clear to me that this is possible, 
> but I seek a more 'sane' way of doing it. What if REXML changes the 
> format of the message slightly in the next version - the regexes won't 
> match any longer. I don't see why there can't be a short way to print a 
> message that is useful to an end user.
>
>
> REXML is praised as *the* XML parsing library of Ruby and is part of the 
> standard library, surely someone noticed its useless error reporting ?!

Why didn't you bother to just look in the code? :-)

[~/src/ruby-1.8.4/lib/rexml/parseexception.rb:]
module REXML
  class ParseException < RuntimeError
    ...
    def position
      @source.current_line[0] if @source and defined? @source.current_line and
      @source.current_line
    end

    def line
      @source.current_line[2] if @source and defined? @source.current_line and 
      @source.current_line
    end

    def context
      @source.current_line
    end
  end
end

-- 
Christian Neukirchen  <chneukirchen@gmail.com>  http://chneukirchen.org