Re: Updating inherited attributes without __construct()

Sorry, I probably should have included the add() function from the parent. As well as all of the parent constructor. Basically the object takes an array of key=>value pairs and parses them into a string for output. When it takes in the array of pairs it needs to check the keys against a list of valid keys. I have no preference on how to store the list of valid keys other than to add more a constructor doesn't need to be called. class parent{ $validkeys = 'name,size'; $attributes = array(); __construct($set){

    foreach($set as $key=>$value){
      if(isValidKey($key)){
        $this->attributes[$key] = $value;
      }
    }

} __toString(){

    $output = "";
    foreach($this->attributes as $key=>value){
      $output .= sprintf(TEMPLATE, $key, $value);
    }

} __set($key, $value){

    if(isValidKey($key)){
      $this->attributes[$key] = $value;
    }

} isValidKey($key){ ...Something goes here... } } class child extends parent{ ...All this needs to do is tack on values 'color,shape' to parent's valid keys... } class grandchild extends child{ ...All this needs to do is tack on values 'cost,location' to child's valid keys... } Most sub classes won't need anything different from their parent but the expanded list of valid keys. Nathan Nobbe wrote:

i dont quite understand this reasoning.. if you want to add some valid keys, based upon the design of the parent, it seems to me the children do have a need for an overridden constructor. if you have accessor methods w/ a consistent naming convention, you could omit the $validKeys array altogether, and determine if a given field is valid based upon runtime introspection. something like this, /// in the parent class protected function isFieldValid($field) { if(method_exists($this, 'get' . ucfirst($field)))

    return true;

else

    return false;

} this will work in all the child classes as well, as long as you stick to a consistent naming convention, and you can of course add a check for a set.. method as well if you like. im not saying this technique is the holy grail or anything, im merely offering it as an alternative to your current solution. -nathan On Thu, Jun 5, 2008 at 12:15 PM, Tyson Vanover <tvanover@pdx.edu> wrote:

I have a class that has a list of valid keys, and an array of values. When

a value is added to the array it's key is first checked against the list of

valid keys (this is to prevent injection issues we have been having later on

in the project). class parent{ private $validkeys = 'title,color,name'; private $values = array(); } That class is inherited by other classes that mostly just have an expanded

list of valid keys. I would like to be able to update the valid key list

without having to craft a constructor for child objects. I would rather not

give each child class the constructor, __construct() { $this->validkeys.= ',setting,...'; parent::__construct(); } since most child classes have no need of a unique constructor.