Private helper concept

Imported From: http://groups.google.com/group/in-portal-dev/browse_thread/thread/a2fe033912676eb5#

Right now In-Portal uses mostly one of 3 class types to do it's job:

• event handler - handles all actions from user side
• tag processor - displays content, that tags generate on templates
• helpers - classes that do jobs specific to both event handler and tag processor

Right now In-Portal uses helper classes of 2 types:

• general - not a unit bound functions inside
• unit bound - unit bound functions inside that either expects initialization with unit info (e.g. BracketsHelper) or unit is given for each called method (e.g. kSearchHelper).

Lately I had troubles with extending "kSearchHelper" to a needs of a specific unit only. Right now there are these problems:

• extending helper class to be used with one unit would cause other units to use same extended helper class (even if they don't need that)
• helper class can only be extended once and if 2+ modules need specific code they can't do it.

Here is an improvement I'm proposing:

1. allow default parameter values in class registration (e.g. don't specify 'build_event' parameter all the time with 'OnBuild' value)
2. add SearchHelperClass => Array ('class' => 'kSearchHelper' ,'file' => '') construct to unit config (if absent will be considered as default)
3. add kBase::getSubObject($class_suffix, $params = Array ()) method, that would internally do this: return $this->Applcation->recallObject($this->getPrefixSpecial() . '_' . $class_suffix, $this->Prefix . '_' . $class_suffix, $params);
4. replace code $this->Application->recallObject('SearchHelper')->performSearch($event) with code  $this->getSubObject('SearchHelper')->performSearch()

There are several benefits from code above:

1. via $this->getSubObject there is possible to easily (very short code piece) to create unit-bound helper class version
2. even shorter unit config class registrations
3. adding unit-specific code to common helper class won't affect other classes who uses that helper