Implementacja interfejów + polimorfizm, książka Profesional PHP5 Opcje

[cojack]

[PHP] pobierz, plaintext 
<?php
interface Band {
      public function getName();
      public function getGenre();
      public function addMusician();
      public function getMusicians();
   }
 
   interface Musician {
      public function addInstrument();
      public function getInstruments();
 
      public function assignToBand();
      public function getMusicianType();
   }
 
   interface Instrument {
      public function getName();
      public function getCategory();
   }
 
   class Guitarist implements Musician {
      private $last;
      private $first;
      private $musicianType;
 
      private $instruments;
      private $bandReference;
 
      function __construct($first, $last) {
         $this->last = $last;
         $this->first = $first;
         $this->instruments = array();
         $this->musicianType = "gitarzysta";
      }
 
      public function getName() {
         return $this->first . " " . $this->last;
      }
 
      public function addInstrument(Instrument $instrument) {
         array_push($this->instruments, $instrument);
      }
 
      public function getInstruments() {
         return $this->instruments;
      }
 
      public function getBand() {
         return $this->$bandReference;
      }
 
      public function assignToBand(Band $band) {
         $this->$bandReference = $band;
      }
 
      public function getMusicianType() {
         return $this->musicianType;
      }
 
      public function setMusicianType($musicianType) {
         $this->musicianType = $musicianType;
      }
 
   }
 
   class LeadGuitarist extends Guitarist {
      function __construct($last, $first) {
         parent::__construct($last, $first);
         $this->setMusicianType("główny gitarzysta");
      }
   }
   class RockBand implements Band {
      private $bandName;
      private $bandGenre;
      private $musicians;
 
      function __construct($bandName) {
         $this->bandName = $bandName;
         $this->musicians = array();
         $this->bandGenre = "rock";
      }
 
      public function getName() {
         return $this->bandName;
      }
 
      public function getGenre(){
         return $this->bandGenre;
      }
 
      public function addMusician(Musician $musician){
         array_push($this->musicians, $musician);
         $musician->assignToBand($this);
      }
 
      public function getMusicians() {
         return $this->musicians;
      }
   }
 
   class Guitar implements Instrument {
 
      private $name;
      private $category;
 
      function __construct($name) {
         $this->name = $name;
         $this->category = "gitary";
      }
 
      public function getName() {
         return $this->name;
      }
 
      public function getCategory() {
         return $this->category;
      }
   }
 
   // Test obiektów
   $band = new RockBand("Czerwone Zmienne");
   $bandMemberA = new Guitarist("Michał", "Zmiennoprzecinkowy");
   $bandMemberB = new LeadGuitarist("Grzegorz", "Całkowity");
 
   $bandMemberA->addInstrument(new Guitar("Gibson Les Paul"));
   $bandMemberB->addInstrument(new Guitar("Fender Stratocaster"));
   $bandMemberB->addInstrument(new Guitar("Hondo H-77"));
 
   $band->addMusician($bandMemberA);
   $band->addMusician($bandMemberB);
 
   foreach($band->getMusicians() as $musician) {
      echo "Muzyk ".$musician->getName() . "<br>";
      echo "to " . $musician->getMusicianType() . "<br>";
      echo "w zespole grającym " . $musician->getBand()->getGenre() . "<br>";
      echo "o nazwie " . $musician->getBand()->getName() . "<br>";
 
      foreach($musician->getInstruments() as $instrument) {
         echo "Jego instrument to " . $instrument->getName() . " ";
         echo "(" . $instrument->getCategory() . ")<br>";
      }
      echo "<p>";
   }
?>
[PHP] pobierz, plaintext 

Nie rozumiem dlaczego zwraca mi taki błąd: Fatal error: Declaration of Guitarist::addInstrument() must be compatible with that of Musician::addInstrument() in /srv/http/ksiazka/1.php on line 23.

Jeżeli nie macie nic do powiedzenia, to nie odpisujcie, nie chce żadnych komentarzy pomyśl, popatrz na 11 i 42 linijke, nie oczekuje tego. Chciałbym po prostu dowiedzieć się gdzie i co jest źle i jak to naprawić, będę bardzo wdzięczny.

Ten post edytował cojack 14.05.2009, 12:55:49