I am working with a directory that contains both data files and marker files. The marker files have the same base name as the data files but a different extension. They are used as markers that identify the data files that are no longer used. As a result, the files exist as pairs unless they are current in which case only the data file is present. An example directory listing would contain:

00000001.did
00000001.mrg
00000002.did
00000002.mrg
00000003.did
[download]

I want to work with all of the current data files so I am using the code below to find the list of data files that does not have a corresponding marker file.

sub unmergedFiles
{
    my $dir = shift;
    my %merged;
    my @files;
    
    # create the hash containing the merged files
    foreach (glob ($dir."/*.mrg"))
    {
        if ( /(\S+)\.mrg/i )
        {
            $merged{lc ($1 . ".did")} = "1";
        }
    }
    
    foreach (glob ($dir."/*.did"))
    {
        unless (exists $merged{lc($_)})
        {
            push @files, $_;
        }
    }
    # return style as per node 311537!
    return wantarray ? @files : \@files;
}
[download]

This code works just fine but I would like the opinion of more learned monks as to how this code can be improved. A couple of things spring to mind:

• There is probably a CPAN module to do this already but I haven't looked as writing the code was educational.
• I am really just comparing the contents of two arrays to find the difference. Have I missed out on a more concise method?
• I am creating a hash by iterating over an array and assigning new hash elements. Is there a better way of doing this?

All comments gratefully received!

inman

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