Object-oriented programming, class switching

<?phpabstract class ParamHandler{protected  $source;p rotected  $param  = array () ; Function __construct ($source)  {$this->source =  $source;} Function addparam ($key, $val)  {$this->params[' $key '] =  $val;} Function getallparams ()  {return  $this->params;} Static function getinstance ($filename) {     //is used to get subclass instances, file types are too long, only                                                        //need to add the IF statement here, and then write the sub-class         if  (Preg_match ("/\.xml$/i",  $filename))  {         return new xmlparamhandle ($filename);      &nBsp;  }        return new textparamhandler ($ filename);} Abstract function write ();   //guarantees that subclasses implement both methods Abstract function read ();}? >

And then the following is the subclass

Class Xmlparamhandle extends Paramhdndle{function write () {}function read () {}}class Textparamhandle extends Paramhdndle {function write () {}function read () {}}}

You can do this when you instantiate it.

$test = Paramhandler::getinstance ("./params.xml");

This will find the corresponding class instantiation based on the incoming Params.xml file.

Object-oriented programming, class switching