From: Marko Schulz <in6x059@...>
Date: 2002-03-17T08:31:54+09:00
Subject: Re: Some potential RCRs

On Wed, Mar 13, 2002 at 01:39:23PM +0900, Sean O'Dell wrote:
> "Bob Alexander" <balexander@rsv.ricoh.com> wrote in message
> news:3C8EC7F5.A4B702C7@rsv.ricoh.com...
> > On the topic of whether ".." and "." should be in our directory
> > listings:
> >
> > Can someone suggest an argument as to why having them in the listed
> > entries is useful?
> 
> That's because ls considers files beginning with '.' to be "hidden."  It
> hides all files beginning with '.' by default.  There is no real "hidden"
> attribute in unix, so it's accepted that files beginning with '.' are
> "hidden" files.

At least GNU-ls has a switch to list all files but '.' and '..': ls -A
 
> A good example of their usefulness would be a simple file browser, say an
> HTML-based file browser.  Each file in a directory displayed shows date, mod
> time and size.  By simply showing this information for each directory entry,
> you can display that information for the current directory and the parent
> directory without having to do anything particularly special.  Also, if you
> attempt to chdir a directory the user selects (in other words, navigate),
> and the user selects '..', they can get to the parent directory.

That is a very special case. Even though it would be extra effort,
such a browser could easily display the parent and current directory
additional. 

BTW: . and .. are not very intuitive names, so a browser would do good
     to  display them in a special way anyhow.
 
> '.' and '..' aren't just artifacts.  If the user has selected a directory,
> it's easier and more efficient to get your stat information from '.' than
> from Dir.cwd(), and it's easier to change to the parent directory by
> performing a chdir('..') than to grab the current working dir and parse it
> to find the parent to chdir to it.

You may use '.' and '..' whether they are returned by Dir::[] or
not. Maybe your code becomes a little bit less portable by doing so,
but this even worse when you always have to test for '.' and '..' in
the return values of Dir::[] or a Dir#each-block.
 
-- 
marko schulz