Drupal Entity and entity_metadata_wrapper()

<?php
$wrapper = entity_metadata_wrapper('node', $nid);
// Uncomment the line below to see all the available properties, requires the Devel module.
// dpm($wrapper->getPropertyInfo());
$sanitized_title = $wrapper->title->value(array('sanitize' => TRUE)); // you don't need to worry about what language the entity is stored as
$raw_text = $wrapper->field_text->value();
$mail = $wrapper->author->mail->value();
$wrapper->language('en')->field_text->value(); // however, if you want to get a translation, you can
$terms = $wrapper->field_tags->value();
$wrapper->field_tags[] = $term;
$options = $wrapper->field_tags->optionsList();
$label = $wrapper->field_tags[0]->label();
$access = $wrapper->field_tags->access('edit');
 
$wrapper->author->mail->set('loopduplicate@example.com');
$wrapper->save(); // necessary after setting values
?>

<?php
// Unpublishes a node.
  $wrapper = entity_metadata_wrapper('node', $nid);
  $wrapper->status->set(0);
  $wrapper->save();
?>

The wrappers always return the data as described in the property
information, which may be retrieved directly via entity_get_property_info()
or from the wrapper:
 
  $mail_info = $wrapper->author->mail->info();
 
In order to force getting a textual value sanitized for output one can use,
    e.g.
 
  $wrapper->title->value(array('sanitize' => TRUE));
 
to get the sanitized node title. When a property is already returned
sanitized by default, like the node body, one possibly wants to get the
not-sanitized data as it would appear in a browser for other use-cases.
To do so one can enable the 'decode' option, which ensures for any sanitized
data the tags are stripped and HTML entities are decoded before the property
is returned:
 
  $wrapper->body->value->value(array('decode' => TRUE));
 
That way one always gets the data as shown to the user. However if you
really want to get the raw, unprocessed value, even for sanitized textual
data, you can do so via:
 
  $wrapper->body->value->raw();