How to Traverse a Directory

Ruby
1

def traverse(root)
Dir.foreach(root) do |file|
next if file[0] == ?.
puts file
traverse(root + ‘\’ + file) if File.directory?(root + ‘\’ + file)
end
end

This is my initial attempt. Two things feel rather wrong:

  1. Is there a simpler way to test the beginning of a string? A
    startsWith?(aString) like method?
  2. I’m iterating through filenames, then appending the path each time.
    Is there a way to get a
    collection of File objects from a directory?

Any other pointers to where I could improve would also be greatly
appreciated.

(I tried posting this twice through Teranews, but it doesn’t seem to
have got through.)

2

Cant really help you but just want to say that
next if file[0] == ?.

is something I did too to get rid of the . and … which
dont really give me helpful info (when i look for real
files or directories for example)

3

This should give you back the entries in a path (dir), so just call it
recursely:

  def get_entries(path)
    dir_entries = nil
    begin
      Dir.chdir(path) do  # get entries in this directory
        dir_entries = Dir.entries(path)
      end
    rescue SystemCallError
      @flash[:notice] = "No such path!"
      redirect_to :controller => 'explorer', :action => 'index'
    end
    dir_entries unless dir_entries == nil
  end

try looking also here: http://gotapi.com/index.html

4

Newbie wrote:

def traverse(root)
Dir.foreach(root) do |file|

You can use Dir #[], #glob, or #entries also. If you use a glob or the
entries method, you can also automatically skip the . and … –
Dir.entries(root)[2…-1] will give you an array of all the files and
subdirs in root, minus the first two (which are always . and …) If you
do that, you can skip the next line.

Check out the docs to see how to use them further:
http://ruby-doc.org/core/classes/Dir.html

 next if file[0] == ?.

This will probably work for most cases in windows (though not always),
but it definitely a bad idea for any other OS (because filenames can
start with a . to mean they should be hidden in normal listing modes).
What I usually use is – next if [‘.’, ‘…’].include? file – which
checks if the full filename == ‘.’ or ‘…’

 puts file
 traverse(root + '\\' + file) if File.directory?(root + '\\' + file)

This is also not very portable. Better to use File.join(root, file)

end
end

Ps. Your directory traverser looks ALOT better than my first one did!

HTH,
Jordan

5

MonkeeSage wrote:

 puts file
 traverse(root + '\\' + file) if File.directory?(root + '\\' + file)

This is also not very portable. Better to use File.join(root, file)

You can also refactor that to this:

puts file = File.join(root, file) # assignment returns its value
traverse(file) if File.directory?(file)

6

Thanks for all the help!

MonkeeSage wrote:

7

On 21.09.2006 11:06, Newbie wrote:

startsWith?(aString) like method?
Like this?
next if /^./ =~ file

  1. I’m iterating through filenames, then appending the path each time.
    Is there a way to get a collection of File objects from a directory?

File objects are for actually reading and writing objects. You can do
Dir["*"] which returns an array of strings.

Any other pointers to where I could improve would also be greatly
appreciated.

Use Find:

irb(main):001:0> require ‘find’
=> true
irb(main):002:0> Find.find(’.’) {|f| puts f}
.
./x
./prj-jar.txt
./jdk-jar.txt
=> nil

irb(main):005:0> Find.find(’/tmp’) {|f| puts f}
/tmp
/tmp/x
/tmp/prj-jar.txt
/tmp/jdk-jar.txt
=> nil

irb(main):008:0> Find.find ‘/tmp’ do |f|
irb(main):009:1* next if File.directory? f
irb(main):010:1> puts f
irb(main):011:1> end
/tmp/x
/tmp/prj-jar.txt
/tmp/jdk-jar.txt

Note, you can also use File.join to portably combine paths.

Kind regards

robert
8

MonkeeSage wrote:

next if file[0] == ?.

This will probably work for most cases in windows (though not always),
but it definitely a bad idea for any other OS (because filenames can
start with a . to mean they should be hidden in normal listing modes).
What I usually use is – next if [‘.’, ‘…’].include? file – which
checks if the full filename == ‘.’ or ‘…’

Good point - perhaps http://www.ruby-doc.org/core/classes/Find.html
should be fixed :wink: