Reworked all the hashes (%files, %ar) into hash references ($files, $ar)

for better clarity. Who uses hashes, anyway?

Added some more sanity and error checking.

symlink-images-by-aspect-ratio.pl

@@ -9,23 +9,40 @@ use Image::EXIF;
 use Data::Dumper::Simple;
 use Math::Round;
 
-$Data::Dumper::Indent = 3;
-
 my $conf = {
     src_dir => "./pics",
     dst_dir => "./links", 
 };
 
+# verify the source dir
+if (! -d $conf->{src_dir}) {
+    print "ERROR: Source directory '$conf->{src_dir}' does not exist. Aborting.\n" ;
+    exit 1;
+}
+
+# verify the destination dir
+if (! -d $conf->{dst_dir}) {
+    print "ERROR: Source directory '$conf->{dst_dir}' does not exist. Aborting.\n";
+    exit 1;
+}
+
 # gather the list of files
 my @list = find_wanted(
     sub { -f && ( /\.jpg$/i || /\.jpeg$/i ) }, 
     $conf->{"src_dir"} 
 );
+if (! @list) {
+    print "No files found.\n";
+    exit 0
+}
 
 # get their information
-my (%files, %ars, $i, $errors);
+my $count = 0;                                                                  # how many files?
+my $errors = 0;                                                                 # how many errors?
+my $ars = {};                                                                   # a hashref that holds all the encountered aspect rations and their number of occurence
+my $files = {};                                                                 # a hashref that holds all the files, their exif data, and their calculcated aspect ratio
 foreach my $f (@list) {
-    $i++;
+    $count++;
     print "Gathering info for image in file: $f\n";
     my $e = Image::EXIF->new($f);
     my $exif = $e->get_image_info();
@@ -56,45 +73,45 @@ foreach my $f (@list) {
     else {
         my $ar;
         $ar = nearest(0.01, ($x > $y) ? $x / $y : $y / $x) unless $error_flag;
-        $ars{$ar}++;
-        $files{$f}->{"ar"} = $ar;
+        $ars->{$ar}++;
+        $files->{$f}->{"ar"} = $ar;
     }
 
     # Append the exif data into hash
-    $files{$f}->{"exif"} = $exif;
+    $files->{$f}->{"exif"} = $exif;
 
     # bump the number of errors
     $errors++ if $error_flag;
 }
 
 print "All images and their EXIF data:";
-print Dumper %files;
+print Dumper $files;
 print "\n";
 
-print "Total images found: $i\n";
+print "Total images found: $count\n";
 print "Images with invalid EXIF data: $errors\n";
 
 print "Aspect ratio information for all images (aspect ratio => number of occurences):\n";
-print Dumper %ars;
+print Dumper $ars;
 print "\n";
 
 # Create destination directories
-print "Creating destination directories.\n";
-foreach my $d (keys %ars) {
+print "Creating destination directories: ";
+foreach my $d (keys %$ars) {
     my $dirname = $conf->{"dst_dir"} . "/" . $d;
-    print "Creating directory: $dirname\n";
+    print "'$dirname' ";
     mkdir $dirname;
 }
 print "\n";
 
 # Symlink
-print "Symlinking source files into destination directories.";
-foreach my $f (keys %files) {
-    next unless exists $files{$f}->{"ar"};
+print "Symlinking source files into destination directories.\n";
+foreach my $f (keys %$files) {
+    next unless exists $files->{$f}->{"ar"};
 
     # construct the symlink name
     my $name = basename($f);
-    my $ar = $files{$f}->{"ar"};
+    my $ar = $files->{$f}->{"ar"};
     my $dest = $conf->{"dst_dir"} . "/" . $ar . "/" . $name;
 
     # symlink