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@xxxxxxx> 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.
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