From: Massimiliano Mirra <list@...>
Date: 2002-03-13T23:03:41+09:00
Subject: Re: Some potential RCRs

On Wed, Mar 13, 2002 at 01:39:23PM +0900, Sean O'Dell wrote:
> 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.

Good points.

> '.' 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.

Easier than all would be a call to a Dir.chparent.  What I'm concerned
about is, is Dir.chdir('..') going to work on Windows, Mac OS X and
all the platform Ruby runs on?  If we want to write easily portable
code, we write File.rename(..., ...) instead of `mv ... ...`, so there
could be a portable way of going up a directory, exactly for the
reason that you'd have to parse the current directory otherwise.

This is similar to the GUI discussions: maybe not all toolkits have an
OpenGL widget (as not all file systems support permissions), but all
toolkits have button widgets (as all file systems support directory
trees and parent directories), we just need to come up with an unified
API that does the latter and hides the system-specific details.

All in all I still feel that the file management routines work too
low-level and shell-like and that we would benefit from some serious
abstractions.  This is the direction I'm thinking in:


joe_dir = Dir.new('/home/joe')

other_dir = joe_dir.parent

p other_dir.name                 # "home"
p other_dir.path                 # "/home" 

joe_dir.entries.each do |entry|
  if entry.directory?
    print "dir:  "
  else
    print "file: "
  end

  print "filename: #{entry.name} (full path: #{entry.path})"
end


Dir#entries would not return an array of strings but an array of
objects, which you could query for information such as name, path,
date, permissions etc. in a much more Ruby-oriented way than with
File#method(filename).



Massimiliano