Module install() $this->registerHook() OR vs. AND

[justinl]

Hello,

I've just started developing with Prestashop and writing my own modules. One question that comes to mind is what is the difference or purpose to using OR or AND when writing the install() method of a module.

Consider these two code snippets:

function install()
   {
       if (!parent::install() OR !$this->registerHook('top') OR !$this->registerHook('header'))
           return false;
       return true;
   }

public function install()
   {
           return (parent::install() AND $this->registerHook('top') AND $this->registerHook('header'));
   }

What is the purpose of using AND or OR? What do they do? All I can figure out is that if you use AND, it installs your module by default into those hooks. Any light shed on this or a link to some documentation would be much appreciated.

Thanks