From: Konrad Meyer <konrad@...>
Date: 2007-10-28T08:48:04+09:00
Subject: Re: NOT reading an entire file into memory

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Quoth Devi Web Development:
> I am trying to write a parser for a text-based file format. Files in
> this format frequently become very large. While the specification
> specifically allows applications to crash on large files, I know
> several people who have taken to editing these files by hand in
> Notepad or other basic text editors. This format is not at all
> friendly for this type of editing, and it is extremely tedious work,
> but their programs all crash due to the size of these files.
> What I really want to know is:
> I had been using File.readline and saving a lot of temporary files via
> tempfile.rb=20
(http://www.ruby-doc.org/stdlib/libdoc/tempfile/rdoc/index.html).
> However, I have heard that File.readline is in fact equivalent to
> File.read.split('\n').each, which would really ruin my purpose of not
> loading the whole file. I'd really like to keep this in ruby, as I
> want to package the whole thing via the wonderful rubyscipt2exe, as
> well as, of course, a standard rubygem.
> What I would actually really love is if there was a way to read lines
> 4 through 7 without reading the whole file.
> My current method has made the program not nearly as beautiful as ruby
> ought to be.
>=20
> -------------------------------------------
> Daniel Brumbaugh Keeney
> Devi Web Development
> Devi.WebMaster@gMail.com
> -------------------------------------------

  f =3D File.open("myfile")
  # skip through 3rd line
  3.times do f.readline end

  Array.new(4).map do
    f.readline
  end

=2D-=20
Konrad Meyer <konrad@tylerc.org> http://konrad.sobertillnoon.com/

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