topical media & game development
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professional-php-05-class.collection.php / php



  <?php
  class Collection {
  
    private _members = array();    //collection members
  
    private _onload;               //holder for callback function
  
    private _isLoaded = false;     //flag that indicates whether the callback
                                    //has been invoked
  
    public function addItem(obj, key = null) {
      this->_checkCallback();      //_checkCallback is defined a little later
          
      if(key) {
        if(isset(this->_members[key])) {
          throw new KeyInUseException("Key \"key\" already in use!");
        } else {
          this->_members[key] = obj;
        }
      } else {
        this->_members[] = obj;
      }
    }
  
    public function removeItem(key) {
      this->_checkCallback();
      
      if(isset(this->_members[key])) {
        unset(this->_members[key]);
      } else {
        throw new KeyInvalidException("Invalid key \"key\"!");
      }  
    }
    
    public function getItem(key) {
      this->_checkCallback();
      
      if(isset(this->_members[key])) {
        return this->_members[key];
      } else {
        throw new KeyInvalidException("Invalid key \"key\"!");
      }
    }
  
    public function keys() {
      this->_checkCallback();
      return array_keys(this->_members);
    }
  
    public function length() {
      this->_checkCallback();
      return sizeof(this->_members);
    }
  
    public function exists(key) {
      this->_checkCallback();
      return (isset(this->_members[key]));
    }
Use this method to define a function to be invoked prior to accessing the collection. The function should take a collection as a its sole parameter. 

  
    public function setLoadCallback(functionName, objOrClass = null) {
      if(objOrClass) {
        callback = array(objOrClass, functionName);
      } else {
        callback = functionName;
      }
      
      //make sure the function/method is valid
      if(!is_callable(callback, false, callableName)) {
        throw new Exception("callableName is not callable " . 
                            "as a parameter to onload");
        return false;
      }
      
      this->_onload = callback;
    }
Check to see if a callback has been defined and if so, whether or not it has already been called. If not, invoke the callback function. 

  
    private function _checkCallback() {
      if(isset(this->_onload) && !this->_isLoaded) {
        this->_isLoaded = true;
        call_user_func(this->_onload, this);
      }
    }
  }
  ?>
[] readme course(s) preface I 1 2 II 3 4 III 5 6 7 IV 8 9 10 V 11 12 afterthought(s) appendix reference(s) example(s) resource(s) _

(C) Æliens 20/2/2008

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