Views templates don't handle attributes

This was very useful, thanks for posting.
Based on this comment I implemented the following to get custom data- attributes on views rows. This is implemented in D7, just posting here in case it's still relevant moving forward.

I added this to template.php:

function mytheme_preprocess_views_view_unformatted(&$variables) {
  $num_rows = count($variables['classes_array']);
  for ($i = 0; $i < $num_rows; $i++) {
    $variables['attributes_array'][$i] = array('#name' => 'data-mytheme-myattributename', '#value' => 'myCustomValue', );
  }

and then I customized a Views style template as indicated above, like this:

<?php
/**
 * @file
 * Default simple view template to display a list of rows.
 *
 * @ingroup views_templates
 */
?>
<?php if (!empty($title)): ?>
  <h3><?php print $title; ?></h3>
<?php endif; ?>
<?php foreach ($rows as $id => $row): ?>
  <div
  <?php if ($classes_array[$id]) { print ' class="' . $classes_array[$id] .'"';  } ?> 
  <?php if ($attributes_array[$id]) { print ' ' . $attributes_array[$id]['#name'] . '="' . $attributes_array[$id]['#value'] .'"';  } ?>
  >
    <?php print $row; ?>
  </div>
<?php endforeach; ?>

And I end up with this output:

<div class="views-row views-row-1 views-row-odd views-row-first" data-mytheme-myattributename="myCustomValue">
...
</div>

Seems to work like a charm. Thanks again!

Edit: removed dpm(); comment in template header.

In Drupal 8 we do know use attributes all over the place. If someone manages to fix the templates without breaking existing templates/sites feel free to post it.

For anyone coming across this, I've come to realize that while this does in fact work, it only allows assigning a single name => value pair per views row. I ran into problems trying to expand the functionality to allow assigning multiple attributes to a single row. I was able to work within this limit on a recent project but I'd love to revisit this and figure out how to do it. I'll post any progress here.

fix formatting.

As the variables $attributes, $title_attributes and $content_attributes are available automatically in every tpl file (see https://api.drupal.org/api/drupal/includes%21theme.inc/function/template...), I've added these attributes, whereever it made sense to me (not every Views template has a wrapping container element, nor elements, where the title or content attributes would fit).

It's a great start, but it'd also be really handy to be able to add per row attributes.

I made the following additions:

views.module

+ function views_process(&$vars) {
+   if (isset($vars['row_attributes_array'])) {
+     foreach ($vars['row_attributes_array'] as $row_number => $row_attributes_array) {
+       $vars['row_attributes'][$row_number] = drupal_attributes($row_attributes_array);
+     }
+   }
+ }

theme/views-view-table.tpl.php

...
- <tr <?php if ($row_classes[$row_count]) { print 'class="' . implode(' ', $row_classes[$row_count]) .'"';  } ?>>
+ <tr <?php if ($row_classes[$row_count]) { print 'class="' . implode(' ', $row_classes[$row_count]) .'"';  } if ($row_attributes[$row_count]) { print $row_attributes[$row_count];  } ?>>
...

Which then allows you to do something like this:

my_custom_module.module

+ function my_custom_module_preprocess_views_view_table(&$vars) {
+   foreach ($vars['rows'] as $row_number => $row) {
+     $vars['row_attributes_array'][$row_number]['my_custom_attribute'] = 'my_custom_attribute_value_' . ($row_number + 1);
+   }
+ }

Obviously this is only for the table format so far, it may be pertinent to include this in the theme files for other formats.

Updated issue summary as dawehner confirmed this is a D7 only issue.

Here's a re-roll of #4 that also adds content attributes to the "view-empty" div.