Facade

by vlado on Tue, 2006-07-25 09:53
Intent
provide a simple interface to a subsystem.
Motivation
a complex system can have many parts that need to be exposed, but it could be confusing ergo - provide a simple interface to the system. For example a read-evaluate-print process of an interpreter
Implementation
Hide the construction of the required objects inside the facade
Example
class rep_facade {
   function __construct() {
     $this->firewall = new firewall();
     $this->reader = new reader();
     $this->evaluator = new evaluator();
     $this->printer = new printer();
   }

   function rep($text) {
     $text = $this->firewall($text);
     $ts   = $this->reader($text);
     $result = $this->evaluator($ts);
     return $this->printer($result);
   }
 }
Complications
The lack of modules and/or nested classes in php means that this is a comfort interface, not an enforcing interface

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