From: Leslie Viljoen <leslieviljoen@...>
Date: 2007-03-23T05:56:48+09:00
Subject: Re: Knocking Lines Out Of A Multiline String

On 3/22/07, Phrogz <gavin@refinery.com> wrote:
> On Mar 22, 9:15 am, "Leslie Viljoen" <leslievilj...@gmail.com> wrote:
> > You could change your lines into an array of lines and then remove the
> > lines that match:
> >
> > lines = []
> > File.new("text.txt").read.each_line {|line|  lines << line }
> > lines.delete_if {|line| line =~ /\/usr\/local\/lib/}
>
> Leslie, as a public service announcement, you should be aware of
> IO.readlines:
>
> C:\>qri IO.readlines
> ----------------------------------------------------------
> IO::readlines
>      IO.readlines(name, sep_string=$/)   => array
> ------------------------------------------------------------------------
>      Reads the entire file specified by _name_ as individual lines,
> and
>      returns those lines in an array. Lines are separated by
>      _sep_string_.
>
>         a = IO.readlines("testfile")
>         a[0]   #=> "This is line one\n"
>
>
> For that matter, you should also be aware of IO.read:
> ---------------------------------------------------------------
> IO::read
>      IO.read(name, [length [, offset]] )   => string
> ------------------------------------------------------------------------
>      Opens the file, optionally seeks to the given offset, then
> returns
>      _length_ bytes (defaulting to the rest of the file). +read+
> ensures
>      the file is closed before returning.
>
>         IO.read("testfile")           #=> "This is line one\nThis is
> line two\nThis is line three\nAnd so on...\n"
>         IO.read("testfile", 20)       #=> "This is line one\nThi"
>         IO.read("testfile", 20, 10)   #=> "ne one\nThis is line "
>
> You should also be aware of the block form of #open, which opens the
> IO object and then closes it when done.
>
> What you wrote creates a new File object and opens it, but never
> closes it. I'm not really sure what badness can result from this, but
> I gather it's not a good idea.

This does sound rather frightening! What *is* the effect of opening a
file and not closing it?
;-)

Also, doesn't the above say that IO.read closes the file afterwards?


-- 
If you could create a machine that copies hamburgers � you put one
hamburger in and two equally good hamburgers come out the other side �
it would be unethical not to do so and make it freely available.