title: include w_thumbnail_src in function?
body: <p>I got a function that automaticly creates a custom field in the post. I have this located in my functions.php.</p>
  
  <p><code>Image</code> is the name of the custom field and <code>HERE</code> is the value. How can I put the function <code>w_thumbnail_src</code> as the variable?</p>
  
  <pre><code>add_action('wp_insert_post', 'mk_set_default_custom_fields');
      function mk_set_default_custom_fields($post_id)
  
      {
          if ( $_GET['post_type'] != 'post' ) {
              add_post_meta($post_id, 'Image','HERE', true);
          }
          return true;
      }
  </code></pre>
  
  <p>and let me add that <code>w_thumbnail_src</code> is a function in the same file that looks like this</p>
  
  <pre><code>function w_thumbnail_src() {
      if (has_post_thumbnail()) {
          $thumb = wp_get_attachment_image_src(get_post_thumbnail_id(), 'emphasis');
         echo $thumb[0]; // thumbnail url
      }
  }
  </code></pre>