From: Xavier Noria <fxn@...>
Date: 2006-08-01T01:54:51+09:00
Subject: Re: Does Ruby need a "line separator" class?

On Jul 31, 2006, at 6:23 PM, Wes Gamble wrote:

> In a pure Ruby (Rails) app, I've had to modify regexps to handle the
> \r\n sequence so that my regexps will work in a Windows environment.
> I'm guessing that this is related to the "file follows runtime
> conventions" in your post.  Meaning that the file that I'm processing
> (which is actually sourced externally) did not conform to C runtime
> conventions when it was written.

Yes, that is an important point.

When we talk about portability as far as newlines is concerned we are  
assuming the newline conventions of the platform and the data match.  
A portable line-oriented script might fail if it is running on Linux  
processing text files from a FAT32 partition that were generated by  
some Windows program. There a lot of common situations when  
conventions may not match. A portable line-oriented script is not  
supposed to handle those situation, a robust line-oriented script  
should do something sensible with foreign conventions.

Web programming is one of them, because you cannot assume anything in  
the input that comes from a text area or an uploaded text file for  
instance. In that case you better normalize first (written on the way):

   normalized_text_area = text_area.gsub(/\015\012/, "\n").gsub(/ 
\015/, "\n")
   # Now text_area has been normalized and all standard line-oriented
   # idioms will work.

In Ruby we are done because "\n" is "\012" everywhere, in Perl that  
gets slightly more complicated because "\n" is eq "\015" on MacOS pre- 
X. But you see the idea and why you do that.

-- fxn (<-- whose article about newlines for O'Reilly is about to  
appear)