For 'wp cache type', use a standard information function, if available, rather than class-sniffing

[OllieJones]

Feature Request

wp cache type retrieves and displays the type of persistent object cache. Make it more easily extensible.

• Yes, I reviewed the contribution guidelines.

Describe your use case and the problem you are facing

For yet another persistent object cache implementation, this one via SQLite (https://github.com/OllieJones/sqlite-object-cache) it would be nice if thewp cache type command returned something more useful than Unknown.

Describe the solution you'd like

It uses an if / else if cascade in wp_get_cache_type() starting at https://github.com/wp-cli/wp-cli/blob/main/php/utils-wp.php#L255 to look for implementation specifics for each known type of cache and guess the cache type.

Proposal: change near line 256 to add the following bit of code. This will use a method in the cache implementation if it's available to get the cache type.

  // Use the get_cache_type method if the cache implements it.
 if ( method_exists( $wp_object_cache, 'get_cache_type' ) ) {
	  $message = $wp_object_cache->get_cache_type();
  
  // Test for Memcached PECL extension memcached object cache (https://github.com/tollmanz/wordpress-memcached-backend)
  } elseif ( isset( $wp_object_cache->m ) && $wp_object_cache->m instanceof \Memcached ) {
    ...

This allows future object cache implementations (like mine) to have support from the wp cache type command without needing to embed any more implementation specifics in utils-wp.php. And, future releases of existing caches can easily adapt.

[danielbachhuber]

Thanks for the suggestion, @OllieJones !

We generally try to mirror core's implementation as much as possible. If core implemented a get_cache_type() method on the main WP_Object_Cache class, we could call that.

Until then, we'd be happy to add some detection for your object cache drop-in. There aren't so many object cache drop-ins that maintaining the list is a problem.