In the end I was able to do more or less what I had in mind at the beginning. This implementation is recursive (I wanted to mix in both things) but behaves like an iterator using the closure: It uses two queues (one for read filenames and another for directories to be read) but when a directory is read it iterates over itself until a file is found; still, the interface is an iterator. 
{
    my @fq;   # files
    my @dq;   # directories
    my $currentDir;

    sub initDir { push @dq, shift; };
    
    sub getNextFile {
        my $f;
            
        if ( $#fq >= 0 ) {
            $f = pop @fq;
        } else {
            if ( $#dq >= 0 ) {
                my $r;       # filename read
                local *D;
    
                $currentDir = pop @dq;
                opendir(D, $currentDir) || die "$currentDir: $!";
                
                while ( defined( $r = readdir( D ) ) ) {
                    next if $r =~ /^\.{1,3}$/;
                    
                    my $ff = $currentDir . '/' . $r;
                    if ( -d $ff ) {
                        push @dq, $ff;
                    } else {
                        push @fq, $ff;
                    }        
                }
                
                closedir D;
                $f = getNextFile();
                
            } else {
                $f = undef;
            }
        }
        return $f;
    }
}

my $dir = "c:/inetpub";

# execution start here

initDir( $dir );
my $f;
my $i = 0 ;
while ( defined( $f = getNextFile() ) ) {
    $i++;
    print "[$i] $f \n";
}

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What do you think about it? is there anything fundamentally flawed with this approach?

In reply to Thank you by l3nz
in thread Turning a recursive function into an iterator by l3nz

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