Bjoern has asked for the wisdom of the Perl Monks concerning the following question:

Hi fellow monks,

> I'm trying to use the following piece of code to get all files in a given directory. What I would like to achieve now is to output the files in THE SAME ORDER as "ls -R" would do.
@DirArray should hold the directories. %Songs the files in a given subdir.
The Problem is, that the contents of @DirArray doesn't have the same order as an "ls -R" output would have. The Information about the directory sequence is lost (I suppose it's because file::find sorts by inodes).

Is there any possibility to use file::find here or do I have to write my own implementation of it?

any hints appreciated,

Bjoern 

my %option = ();
my %Songs =();
my @DirArray;
my $DirIndex==0;
my $CurrentDir;
my $Artist;
my $Index=1;

getopts("d:", \%option);
sub produce_array {
  if (-d $_) { 
    $CurrentDir=$_;
    $DirArray[$DirIndex]=$_;
    $DirIndex++;
    };
  if (-f $_) {
    push (@{$Songs{$CurrentDir}},$_);
    };
  }

find (\&produce_array, $option{d});

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Re: file::find and ordered output
by broquaint (Abbot) on May 13, 2002 at 09:15 UTC
    An option would be to munge your data before it gets passed to the produce_array() function with the preprocess option 
    find({
    wanted     => \&produce_array,
    preprocess => \&munge_data,
}, $option{d});

    [download]
    See the File::Find manpage for more detail.
    HTH

    _________
    broquaint

[reply]
[d/l]
      I had a look at the manpage (it wasn't the first ;-) but couldn't quite understand how this (preprocess) would help me in my problem.

      quoting the man page of "file::find => preprocess"

      The value should be a code reference. This code reference is used to preprocess the current directory. The name of currently processed directory is in $File::Find::dir. Your preprocessing function is called after readdir() but before the loop that calls the wanted() function. It is called with a list of strings (actually file/directory names) and is expected to return a list of strings. The code can be used to sort the file/directory names alphabetically, numerically, or to filter out directory entries based on their name alone. When follow or follow_fast are in effect, preprocess is a no-op.

      "This code reference is used to preprocess the current directory."

      How can it affect the order of the directory processing?

      pondering

      Bjoern
[reply]
        How can it affect the order of the directory processing?
        Its effect is that it changes what is passed to the wanted() coderef e.g 
        find({
    preprocess => sub { return sort { $b cmp $a } @_ },
    wanted     => \&process_array,
}, @ARGV);

        [download]
        This will sort the directory listing that process_array() gets in reverse alphabetic order. So basically the preprocess option allows you to change what the wanted() function receives from changing it's order to removing unwanted directory entries.
        HTH

        _________
        broquaint

        update: changed <=> to cmp in the sort() (thanks ariels)

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