From: Massimiliano Mirra <list@...>
Date: 2002-01-13T11:51:09+09:00
Subject: FileHandle (was: Re: Dir.entries have no home)

On Sun, Jan 13, 2002 at 10:00:07AM +0900, Massimiliano Mirra wrote:
> Some afterthoughts...
> log = FileHandle.new('/home/joe', 'program.log')
> 
> log.location		=> "/home/joe"
> log.name		=> "program.log"
> log.path		=> "/home/joe/program.log"
> 
> log.location = '/home/joe/subdir'
> 
> log.location		=> "/home/joe"
> log.commit		=> true
> log.location		=> "/home/joe/subdir"
> 
> log.path = '/home/joe/otherdir/othername'
> log.commit		=> true
> 
> log.location		=> "/home/joe/otherdir"
> log.name		=> "othername"
> 
> log.location = '/file_in_root_dir'
> log.commit		=> false
> 
> log.location		=> "/home/joe/otherdir"

Still talking to myself.  LOL

I sketched an implementation.  This month's Ruby slogan for me is
``...makes it faster to code it than to talk about it.''

I apologize for the length.  I didn't just upload somewhere and put a
link in the RAA because I still consider this matter worthy of
brainstorming.

See the test at the end for an example of usage.

Massimiliano




require 'ftools'

class FileHandle
  def initialize(*args)
    case args.size
    when 1
      # Initialized with a path
      #
      path = args.shift
      location, name = File.dirname(path), File.basename(path)
    when 2
      # Initialized with a location directory and a file name
      #
      location, name = args.shift, args.shift
      path = File.join(location, name)
    else
      raise ArgumentError
    end
    
    @stat = File.stat(path)

    @info = {
      :location => fill(location),
      :name     => fill(name),
      :path     => fill(path),
      :mode     => fill(@stat.mode),
      :gid      => fill(@stat.gid),
      :uid      => fill(@stat.uid)
    }
  end

  def fill(with)
    { :old => with, :new => with }
  end
  private :fill
  
  def location=(new)
    @info[:location][:new] = new
    @info[:path][:new]     = File.join(@info[:location][:new], @info[:name][:new])
  end

  def name=(new)
    @info[:name][:new] = new
    @info[:path][:new] = File.join(@info[:location][:new], @info[:name][:new])
  end
  
  def path=(new)
    @info[:path][:new]     = new
    @info[:name][:new]     = File.basename(@info[:path][:new])
    @info[:location][:new] = File.dirname(@info[:path][:new])
  end
    
  def method_missing(method_id, *args, &block)
    if @info.keys.include? method_id
      # Read from @info hash
      #
      which = args.shift || :old
      @info[method_id][which]

    elsif method_id.to_s =~ /(\w+)=/ and @info.keys.include?($1.intern)
      # Assign to new values in @info hash
      #
      @info[$1.intern][:new] = args.shift
      
    elsif @stat.respond_to? method_id
      # Act as a proxy for @stat
      #
      @stat.send(method_id, *args, &block)

    else
      super
    end
  end    

  def commit
    @info.each do |what, entry|
      if entry[:old] != entry[:new]

	case what
	when :path
	  File.mkpath location(:new) unless FileTest.exists? location(:new)
	  File.move path(:old), path(:new)

	when :mode
	  File.chmod mode(:new),     path(:old)

	when :gid
	  File.chown nil, gid(:new), path(:old)

	when :uid
	  File.chown uid(:new), nil, path(:old)
	end

	entry[:old] = entry[:new]
      end
    end
    @stat = File.stat(@info[:path][:old])
  end
end


if $0 == __FILE__
  require 'Lapidary/TestCase'

  class TestFileHandle < Lapidary::TestCase
    def testLocationChangesPath
      home = ENV['HOME']

      system("touch #{home}/testfile")
      Dir.mkdir("#{home}/testdir") unless FileTest.exists?("#{home}/testdir")

      h = FileHandle.new("#{home}/testfile") # can also be written as new(home, "test")
      
      assert_equal home, h.location
      assert_equal 'testfile', h.name
      assert_equal "#{home}/testfile", h.path

      h.location = "#{home}/testdir"
      h.commit

      assert_equal "#{home}/testdir", h.location
      assert_equal 'testfile', h.name
      assert_equal "#{home}/testdir/testfile", h.path  
    end
  end
  
  require 'Lapidary/UI/Console/TestRunner'
  Lapidary::UI::Console::TestRunner.run(TestFileHandle)
end