[jdom-interest] End-of-line sequence.

Michael Kay mike at saxonica.com
Tue Nov 15 01:17:28 PST 2011

The only real case I can see for using \r\n is that if you use \n, you 
can't view the output in Notepad (and presumably a few other diehard 
Windows applications).

Making a change will break a few people's unit tests, but no real 
applications should be dependent on the precise bitstream.

Using \r\n does seem a bit quirky, but I can't see that it does any harm.

-0, if that's an allowed vote.

Michael Kay

On 15/11/2011 01:29, Rolf wrote:
> Hi all.
> JDOM has been merrily using "\r\n" as an end-of-line sequence in the 
> XMLOutputer since 'forever'. The XML Spec indicates that all 
> end-of-line sequences should be normalized to a single '\n': 
> http://www.w3.org/TR/REC-xml/#sec-line-ends The wording is such that 
> XML parsers should clear out any extra '\r' characters if there are 
> any, so it is not as if the code is completely broken.
> But, I think it makes sense to follow the spec, and avoid having 
> different XML compared to other systems.
> I propose changing the line separator to follow the spec, but this has 
> a very large impact on anyone who has expectations on JDOM having a 
> particular line-terminator, even though they shouldn't...
> I have filed https://github.com/hunterhacker/jdom/issues/53
> The original decision was made by Elliotte: 
> http://markmail.org/message/gv7m3xjgrkomrfe7   (it's worth noting that 
> it was changed from the 'platform default' to the constant '\r\n' to 
> create some consistency too).
> vvv quote vvv
> The one open question in this version is what to use for a line 
> separator. Right now I'm using \r\n since that's most cross-platform 
> compatible and friendliest to various network protocols. However, \n 
> alone might be slightly friendlier to XML parsers. Another possibility 
> is to ask for System.getProperty("line.separator"). However, I'm 
> loathe to make the output platform dependent. What do people think?
> ^^^ quote ^^^
> Also, the commit introducing this has interesting comments: 
> https://github.com/hunterhacker/jdom/commit/958fb22a4c7088b82f0d48a933bdf4e5c6806151#L0R173
> Two issues I see:
> 1. "\r\n" was chosen for 'Network protocol' friendliness... is this 
> still a valid argument?
> 2. is it OK to change the standard format of all the XML that JDOM 
> produces? (I have been really careful (so far) for the most part to 
> ensure all whitespace (including indents and EOL/EOF is not changed) ).
> I see changing the default EOL as being an easy decision, especially 
> since users can still change it back easily on their Format instance.
> advantages:
> 1. Most XML tools do not use "\r" values - better compatibility?
> 2. XML output will be slightly smaller - ;-)
> 3. XML produced by 'other' outputters (currently the StAX outputters) 
> can be compared directly with XMLOutputter for testing/compatibility
> disadvantages:
> 1. people may have 'baselines' that contain \r\n terminators, which 
> will then be different from JDOM's default output.
> 2. there may be some (obscure) protocols that require \r\n terminators 
> and users of JDOM2 will have to override the EOL to be '\r\n' for those.
> Anyone have comments/suggestions?
> Rolf
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