From: Ron Coutts <rcoutts@...>
Date: 2003-12-16T07:16:23+09:00
Subject: Re: Extracting multiple lines from a file



> -----Original Message-----
> From: Berger, Daniel [mailto:djberge@qwest.com] 
> Sent: December 15, 2003 2:53 PM
> To: ruby-talk ML
> Subject: Re: Extracting multiple lines from a file
> 
> 
> > -----Original Message-----
> > From: Ron Coutts [mailto:rcoutts@envistatech.com] 
> > Sent: Monday, December 15, 2003 2:14 PM
> > To: ruby-talk ML
> > Subject: Extracting multiple lines from a file
> > 
> > 
> > This should be an easy question for Ruby-heads but I can't 
> > seem to easily find the answer.  I need to extract multiple 
> > lines from a file where the lines are delimited by some other 
> > text.  For example, with file contents as shown below I'd 
> > like to extract the content between the BEGIN_FOO and END_FOO 
> > lines.  Can anyone tell me how to do that?  
> > 
> > BEGIN_FOO
> > Some foo stuff here.
> > More foo stuff.
> > END_FOO
> > 
> > I've done this before in Perl (can't remember the syntax) so 
> > I'm thinking it should be possible in Ruby.
> > 
> > Ron
> 
> See the second argument to IO#readlines.  Or, you can set $/ 
> manually -
> same as Perl. :)
> 
> Regards,
> 
> Dan

Thanks for the quick reply Dan, but I may not have been clear as to what
I'm trying to do.  IO#readlines allows one to read lines and specify the
line delimiter (which is usually '\n').  I'm trying to extract the
content between the lines BEGIN_FOO and END_FOO within a file where the
lines are delimited with '\n'.

As I look at the problem further, it seems like Ranges may be part of
the solution.  In the Pickaxe book by Dave Thomas and Andrew Hunt they
give this example where a file (named "ordinal") containing the words
'one' through 'ten', one word per line, is parsed (page 84):

file = File.open("ordinal")
while file.gets
  print if /third/ .. /fifth/
End

Unfortunately this code snippet is buggy as it prints out all ten lines
of the file, not just lines three through five as mentioned in the book.
So I'm still stuck on this problem.  

I've seen Dave Thomas post on the list.  If you read this Dave, do you
have any pointers for me or the fix for the code snippet above?  Any
help would be appreciated.

Thanks,
Ron