[entity] introduce a new 'adapters' registry This changeset introduces the notion in adapters (as in Zope Component Architecture) in a cubicweb way, eg using a specific registry of appobjects. This allows nicer code structure, by avoid clutering entity classes and moving code usually specific to a place of the ui (or something else) together with the code that use the interface. We don't use actual interface anymore, they are implied by adapters (which may be abstract), whose reg id is an interface name. Appobjects that used to 'implements(IFace)' should now be rewritten by: * coding an IFaceAdapter(EntityAdapter) defining (implementing if desired) the interface, usually with __regid__ = 'IFace' * use "adaptable('IFace')" as selector instead Also, the implements_adapter_compat decorator eases backward compatibility with adapter's methods that may still be found on entities implementing the interface. Notice that unlike ZCA, we don't support automatic adapters chain (yagni?). All interfaces defined in cubicweb have been turned into adapters, also some new ones have been introduced to cleanup Entity / AnyEntity classes namespace. At the end, the pluggable mixins mecanism should disappear in favor of adapters as well.

/* -*- sql -*- 

   mysql specific registered procedures, 

*/

/* XXX limit_size version dealing with format as postgres version does.
   XXX mysql doesn't support overloading, each function should have a different name
       
   NOTE: fulltext renamed since it cause a mysql name conflict
 */

CREATE FUNCTION text_limit_size(vfulltext TEXT, maxsize INT)
RETURNS TEXT
NO SQL
BEGIN
    IF LENGTH(vfulltext) < maxsize THEN
       RETURN vfulltext;
    ELSE
       RETURN SUBSTRING(vfulltext from 1 for maxsize) || '...';
    END IF;
END ;;