PHP Pattern Design

1, Policy mode

2, individual mode

3, Factory mode

4, Observer mode

1<?PHP2 classexchangerate3 {4     Static Private $instance=NULL;5     Private $observers=Array();6     Private $exchange _rate;7 8     Static functiongetinstance ()9     {Ten         if(Self::$instance==NULL) OneSelf::$instance=Newexchangerate (); A         returnSelf::$instance; -     } -      Public functionRegisterobserver ($obj) the     { -         $this->observers[] =$obj; -     } -      Public functiongetexchangerate () +     { -         return $this-exchange_rate; +     } A      Public functionSetexchangerate ($new _rate) at     { -         $this->exchange_rate =$new _rate; -         $this-notifyobservers (); -  -     } -     functionnotifyobservers () in     { -         foreach($this->observers as $obj) { to             #code ... +             $obj->notify ($this); -         } the     } *  $ Panax Notoginseng } -  the classProductitem + { A      Public function__construct () the     { +Exchangerate::getinstance ()->registerobserver ($this); -  $     } $      Public functionNotify$obj) -     { -         if($objinstanceof exchangerate)Print"Received update!\n"; the     } - }Wuyi  the  -  Wu $a=NewProductitem (); - $b=NewProductitem (); AboutExchangerate::getinstance ()->setexchangerate (4.5); $  -  -  -?>

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PHP Pattern Design